Interesting, Bob, that you should mention the Orbe (and I believe this also applies to the Gyrodec), in that the record clamping system is integral to the design of the turntable itself, and well-thought out, thus not simply something that's been added later, as an afterthought, which is often the case with these things...
That, for me, is key to the likely (sonic) success of any record clamping
system ['system' being the operative word].
In that respect, it really needs to be factored into the design of the turntable, from the ground up. I'm surprised though, that you can't hear any difference without it, as anytime I've tried it with an Orbe, the sound, with the clamp fitted, has always been no-brainer better!
Marco.