Huge difference. The entire feel of the switch is different. The Cherry browns feel more mechanical and are a bit louder...really hard to describe the difference better than that.
I'll second this. I have a Realforce 55g (for less than a week) and a Cherry brown Filco (for about 2-3 weeks). There's a lot more different about them than how many nickels it would take to depress the key. The switch feel, key feel, sound, everything is different.
I hate to say it, but my Filco feels like a toy compared to my Realforce (and my model M), and it's not just a subliminal effect because of the price of the Realforce. I don't dislike the Filco, so I don't want Cherry lovers burning me at the stake. I still plan on trying a board with Cherry clears. I have also not compared browns in PCB vs. plate mounted - only the Filco. I'd love to try PCB-mounted browns as well.
When I first started typing on my Realforce an analogy came to mind. I find the Realforce is kind of like a sport package BMW or a Porsche. It's a fairly capable and responsive car but they also manage to keep it from being harsh and jarring despite tightness and lots of road communication - it just works. There are other cars out there that reviewers say are faster, or handle better, or "do the same thing" for less money but when you actually drive them you can tell the difference. I'm not talking about price tag, I'm talking about character. If I just wanted to say it was expensive I could say it was the Ferrari or Rolls of keyboards - that's not my point. It has a solid, quality feel with easy to press but tactile keys, no binding and a muted "thocky" sound that's a pleasure to use. It's responsive, yet sophisticated, and communicates "quality" all around without bling or unnecessary flashiness.
My wife, who has been "meh" about all of the keyboards I've been fooling around with since getting serious about this said "ooh, this is nice" when I hooked up the Realforce. She's stated a clear preference for the Realforce.
Geez, Topre should pay me...