I had a Topre all-45g board for over a year, and just a couple of weeks ago, purchased a Filco MJ2 with MX Browns.
It seems you already made up your mind, but I'd just like to put in my 2 cents for other readers...
One of the most often-heard criticisms of MX Brown switches is that they feel "scratchy", but honestly, when I put on a set of PBT's on my MX Browns, they felt MUCH better. They still feel scratchy - that's the nature of the stem, of course - but the PBT keycaps give them a much more solid/consistent feel. Whereas with the ABS, as others have mentioned, the switches feel kind of messy.
That said, IF I PUT ON A SET OF PBT's on the Filco MJ2, they come pretty close to Topre. But if you do buy a set of them (at least dye-sub, which is what I got) for the Filco, they're actually MORE expensive ($150 + $100) than a Topre board ($220 to $250 at EK), so, really... it's hard to say that Topre's are "overpriced" or a "rip-off" compared to other boards. It's apparent that what makes Topre boards so expensive are the PBT dye-subs, and given that a set of dye-sub PBTs for MX switches cost $100, I really have no problem with the price I paid for the Topre board.
But comparing a Filco MJ2 with PBTs, and a Topre Realforce, in terms of BUILD QUALITY, I have to give the edge to the Realforce. The board is just an absolute beast, and does not flex, while the Filco I can still flex just a bit. And then the keycaps... yes, even though I've put on a set of dye-sub PBTs on the Filco MJ2, those PBTs are NOT the same as the PBTs on Topre Realforces. Now that I've had a chance to buy "other" PBTs (the one's I got for my Filco), I really have to say, the Realforce PBTs are absolutely fantastic. The PBTs on my Filco seem cheap and thin in comparison (yet they go for $100)!
But as for positives to the MX Brown switch over Topre, what I really love about MX Brown switches is that they are much easier to press than Topre switches. Yes, the actuation force might be the same, but I think Ripster (was it?) always made a distinction between "actuation force", and "work". Supposedly, IIRC, that while the actuation force of the switches may be the same, the "work" required to press on them are different, and that may be what I'm feeling now. I'll have to guess that it has something to do with the fact that Topre switch tactility points are solely at the top, whereas with the MX Brown switch, you slide down the switch first, and then feel the tactility as you travel down. I just love how easy it is to press on MX Brown switches, I really do.
Does it mean that I LIKE the MX Brown switches more than Topre switches? Not necessarily. I've, again, owned the Filco for just a couple of weeks, so I can't really make that judgment yet. If there is one thing that I dislike about MX Brown switches is that it's changed my typing form. I don't know how to explain it exactly, but I'm seeing that my hands are figured differently than they are when typing on the Topre board, and I think my Topre form is slightly more comfortable. I may see (this is not a definite) issues with typing on my MX Browns for long periods of time in the future.
So, there you have it. In terms of value, they are pretty neck and neck - maybe a slight edge to Topre because of build quality. In terms of build/switch quality, I give the CLEAR edge to Topre. In terms of subjective "which keyboard do I personally like?", it's a TBD at the moment.