I just received my new 87U 55g, I also have a silenced, lubed, and packed 45g HHKB.
As a Topre fanboy, I can honestly say I am not impressed with this board. Directly comparing it to my HHKB, the only positive I can pull from it is that 55g feels extremely crisp compared to 45g. Everything else feels cheap. The case flex towards the bottom is noticeable, the bottom row modifiers wobble like no other, and there is virtually no thock to this keyboard at all. It pretty much solidifies my thought of me hating stock Topre, but loving silenced and lubed Topre. It really is a totally different feel and sound, and after using this stock 87U for a day really makes it a necessity for me.
I stopped using MX boards for the exact reason that they all felt cheap and sounded awful to me, this is not much better. Feel wise, it's way better than any MX switch I have used, but the main reason why I love Topre is for that "THOCK", and this just lacks that completely.
I planned on adding this board to my collection but I honestly don't see myself buying hyperspheres for it and spending the time to lube it, so I am instead going to transplant the 55g cups to my HHKB and sell this as is with 45g/55g to get some of my money back.
Mod Edit: if you decide to sell, you need to list it properly in the Classifieds.