I've actually got both a Filco tenkeyless with cherry blues and a Razer Blackwidow (long story, but I bought the BW as a backup while waiting for my Filco to get back to me). I'm seriously considering sending the BW back. The Filco, for me, has a much crisper feel, while the BW just feels mushy by comparison.
I keep getting caught in that weird place on the switch where I don't come back up far enough for the "click" to actuate, but the key press still registers. This only seems to happen on the BW and not the Filco. This could be an odd side-effect from typing on a Model M for quite some time, however.
Also, as has been said in reviews, the stabilizers on the space and shift keys are not as tight as on the Filco, and the keys themselves seem to be looser and wiggle more.