Interesting to hear your experience with the Type Heaven vs Realforce. I have some sort of Topre Japanese board that I got for 'cheap' (relatively Topre speaking) to get a feel for Topre, but hadn't taken the plunge yet on a real board. I was leaning towards the RF anyways, but this definitely gives me something to think about if I see a deal.I bought the Topre Type Heaven and, while it is okay, it cannot compare to the Realforce Topre in feel, imo. I now use the Topre Realforce 87U which is the best keyboard I've tried.
I did own a Unicomp keyboard. It arrived with something rattling inside and the workmanship seemed a little 'rough'. It stopped working after a year. It's better to buy a real IBM keyboard if you want to own a buckling spring in my humble opinion.
Oh, and I hear you on the Unicomps--they're definitely no IBM/Lenovo. I have identical 101 layout IBMs and a Unicomp and there definitely is a difference in refinement--much more so than any difference between the various years of the Model M.