My FC660C still works like it was new. However, TBH, I don't really use it that much, as I prefer my HHKB. I have the FC660C attached to my wife's computer, and she uses it often, and she likes it. IMO, it hasn't changed at all since it was new. It still feels great. My only complaint today, is the same as the first day I got it, which is that I wish there was a set of replacement keycaps for the FC660C, since the beige-on-dark grey color scheme is completely unappealing. In fact it breaks the number one rule of fashion: it's boring. It is so boring that it's beneath Leopold's standards, IMO. They are a Korean keyboard company making keyboards in the golden age of Korean keyboards, and yet they gave us boring. It is so boring, it could have only been produced by a committee of scared, middle-aged men in a conference room, who were all seeking the "safest" design, a designed that meekly say of itself: "I'm an ubotrusive, dark grey corporate drone." IMO the guys at Leo forfeited their chance to do something great with the look of the FC660C. However, everything under the keytops is excellent.
I still wish it felt like the HHKB. But I still like it a lot (it's been my daily driver at work for the last couple of weeks).
Can you explain by feel different to someone who hasn't tried either hhkb or fc660c?
My experience in mechanical boards:
I have tried cherry m8, m9, my, mx (all standard except for green), alps white linear & complicated, monterey blues (got my 5181 and wow I LOVE it omg)
The click on the monterey blues isn't too loud, I like the way I only bottom out when typing hyper fast with my fat fingers (I want to try greens for that extra resistance, or modded m9's inverted to be tactile with black MY springs 
)
I would be using it for a work driver, but if I like the experience I might become a convert altogether.
Using a TT Meka with mx black at work right now just so I am not stuck on a crappy dell membrane.
Well, the Topre switches feel better than any MX switch IMO. It is impossible to explain the feeling of a keyswitch in words. But if you are looking for a comparison, I would say Topre's feel like MX Browns, without that "grittyness", also the tactile bump comes near the top of the keystroke, instead of in the middle like with MX browns. Also I would say that Topre switches feel a bit better than lubed ergo clears, which are IMO, an MX approximation of the feeling you get from Topre. I dunno if you've had the opportunity to try lubed ergo clears, but that is the closest you can get with Cherry, IMO.
Some people say Topre feels like MX red, which is not really true. The only similarity with MX reds is that it's fairly effortless to type with Topre, especially the silent variable switches available on the RealForce 87U. So in that respect, the ease of typing, is similar to reds. Although there is a tactile bump to the Topre that is not present in the MX red. I dunno if this helps at all. The only way to know is to try Topre for yourself. A meetup would be a great way to try somebody's Topre keyboard. Or just get one. You will not be sorry if you do. The worst reaction I've seen is that people like the Topre switch, but don't feel it was worth the extra price over the MX (which is kind of ridiculous, IMO, b/c the same people will pay $600 for a custom Cherry MX keyboard, which is more expensive than any Topre.)
One other thing about HHKB and FC660C is that they are 60% keyboards, and are smaller than TKL, and have a fn layer. Also HHKB has it's distinctive key layout, which is superior to traditional layout, but requires a period of adjustment.
