There is always this thread for those wanting to know approximately how long Topre keyboards last before rubber starts stiffening up. To me I honestly believe such changes are subtle if anything but I'll leave that decision for the viewers to decide: http://geekhack.org/index.php?topic=27474.0
IMO its really awesome that instead of losing the feel of the topre swtich . The longer you use it the better it feels
I actually quite like the feel of typing on Topre after coming from a day out in gardening operating handheld machinery (like whipper snippers). Typing on my old membrane keyboard that I was using prior to HHKB made me feel even more sore as I had to hit harder but on Topre imo it feels softer to hit and therefore doesn't place that much burden on my arms, etc.
Ultimately if one is concerned about rubber stiffening, there is always the lube route, that's for sure.
+1 on Filco. Topre is a short hype 
Rubber wears out quickly, and it's got many issues like inconsistent feel (difference in weight in "uniform" keyboards is +- 15g, and you can't RMA that as that's what spec says), crappy ABS spacebar (and whatever you do to your Topre, put it in gold plated case, you will still have shiny crappy ABS space bar) and very expensive and hard to get replacement keycaps. Also if you do something to rubber under one of the keys forget about getting a replacement just for that - you will have to get whole board to fix one key
It does have unique feel though and if you're lucky (I somehow was with my HHKB which is quite consistent, Realforce was so inconsistent I just couldn't stand it) it's ok for some time, at least until it wears out. When worn it becomes really weird. Less used keys become heavier due to rubber stiffening, and mostly used keys become linear. I have this with my HHKB and as long as I'm using it only for travel I can live with it, but if there were any MX based 60% board with usable layout (I know GH60 is cool but I can't get/make one yet), I'd sell my HHKB straight away.
With Filco it's all consistent, keyboard is very well made, stock keycaps are no better than QFR (i mean you can feel they're cheap, but they look and work ok) but you can replace them with excellent ones, better than Topre for relatively low cost and Filco + nice PBT caps will still cost half price of Realforce
If you have the JP/JIS variant of the HHKB (this may also very well extend right onto Realforce JIS keyboard for instance as well but I am not sure) the spacebar is not likely to shine any faster than a full sized spacebar. It was said before the JIS spacebar (yes that exact puny spacebar that people loathe) is not made of ABS but PBT.
About the nice PBT caps for Cherry MX, that is another one small bad thing about them featured on many boards. When people want durability at an affordable price they find PBT caps are rare than ABS. That said the majority of the Topre boards are using PBT. Even though Topre boards are not as expanse as Cherry MX range, it seems as though more thought has been taken into Topre boards. Also, the majority of the Topre boards comes with sublimation printing on top of PBT. Realforce also offers lasered printing but the majority still remails sublimation. All modern HHKB are sublimated.
I am not taking this out specifically on you but I thought there were some things notable in what you said that I couldn't let go of.
On a last but a very minor note, it is inevitable that rubber domes will stiffen over time. At the same time it is not like there is nothing that cannot be done to counteract (temporarily) the stiffening. It was once said that HHKB Pro are the professional end of keyboards designed for those professionals in mind rather than those looking to make the most out of some high end equipment and thinking they would last an eternity. I have here, a pair of Sony MDR-7506 studio monitors. These were once heralded as professional choice for audio reproduction by professionals within the audio realm. Now these pair of cans have leather sort of like wrapping (more like faux leather imo but anyway), and throughout over use I have noticed these leather started peeling off slowly eventually leading to what is now just some simple foam padding. I do admit it is a bit of a pity that the nice bit of leather that was once wrapped around it has now largely disappeeared but is it something that I can count as something that I would regret with my purchase? no. How does this relate to Topre boards stiffening over time? think about professionals whom probably would not be hanging onto the same piece of stuff over great periods of time and even if they would, they wouldn't be moaning about the said product that has loss its appeal.
Professional equipment at the end of the day does not necessarily mean it would last an eternity, neither does forking out lots of money for a keyboard technology would necessarily mean that you will never have any sort of issues over the use of the said product. On the other hand, whilst one has professional equipment in their hands it is best for one to embrace the quality of the said product despite of its shortcomings.
Now in response to OP, wise choice! now you will soon be able to understand what it feels like to use a Topre board. I would also do the same thing if I could (but with Cherry MX for instance) but after tasting Topre board it seems like the best idea for me is to hold out for a worthy enough Cherry MX board to contend with my Topre.
I think this post is quite wise. Yes, professional quality never means it will last much longer. It means it is of a quality that professionals appreciate. As opposed to a quality that you can put up with if you only use the keyboard 30 minutes a day.
Once in a while I am in a situation (Eg public library) where I am forced to use a rubber dome. It feels so nasty, I want to stop typing right away.
Now that's un-professional quality.
Will professional quality stuff last longer than amateur quality stuff? I think almost certainly so. Will it last for decades? Not necessarily.
Rootwyrm has a post where he talks about wearing out a Model M after several years. But his usage is scary (I think he said 30,000 words a day; my memory may be flawed).
Glad someone else here agrees with me. Professional stuff by no means is cheap but at least for an average bloke, to taste the joys of professional products is something that money can only buy.
I am sure in a few years time when my HHKB starts facing some issues with rubber stiffening or the like, regardless of how I treat the situation I will never forget the joys of using HHKB even though it was costly.
As for Rootwyrm, holy #$%&'()!! I don't think I'll ever achieve 30,000 words a day but those Model M were supposed to last after several million keystrokes. The amount is way more than Cherry MX or Topre based switches and yet for one to wear Buckling Springs out like that is insanity to me
. To each their own I guess.
Topre switch is similar to a very quiet Cherry brown one, but with double price.
If you have plenty of money, buy a Realforce. If not, a Filco brown is also sufficient.
You decide.
One does not simply compare topre with cherry
+1 (even though I have yet to try out Cherry MX switches). I am sure there are plenty of other people that are already recommending Topre (especially silenced ones) for those who quiet keyboard in various other forum threads.
Also Realforce is not that much more expensive if you were to source it straight from Japan for instance. The only trouble is that getting through EU customs for instance would be fun. Then there's brands like Leopold FC660C or Type Heaven for those looking to get Topre on a budget. Realforce is not overpriced imo, compared to HHKB Pro (at this current rate).
