I've owned an EAA Witness 10mm, Glock 20C and a couple of 10mm 1911s (but not the Razorback).
Some thoughts:
I owned and liked the EAA Witness 10mm. Average accuracy varies wildly gun-to-gun, though, and the stock sights and triggers aren't so hot. D.R. Middlebrooks and EGW will do custom work to fix these issues to varying degrees, but the "top end" accuracy & trigger potential of these guns is limited compared to, say, a 1911. Furthermore, both D.R. Middlebrooks and George Smith at EGW have commented that the design isn't really strong enough for the 10mm Auto cartridge over the long haul when I talked to them. Not what you'd expect to hear about such a big hunk of steel (especially from the few people who stand to make a buck working on Witness guns), but apparently the lockup just ain't that strong. Too bad, since the thing is great to shoot... the ergonomics and all that steel make it a great recoil sponge.
The Glock 20C was an excellent performer, though the porting on the "C" versions is a waste of time in my opinion. On the other hand, the huge grips are unsuited to most human hands, and Glock triggers will always suck.
Both the Razorback and the Kimber Stainless Target II guns have had reports on 1911forum.com of being unreliable out of the box. People have a right to expect more from close to $900 guns. Having a pre-Series II Kimber converted to 10mm by a pistolsmith would cost the same or less, and result in a more reliable product. Or you can look around for a good deal on a Delta or S&W 10xx series gun.