Here's a post I just did on another thread (Sony R550A TV) where we're currently discussing the Darbee>>>>>>
Obviously you know that screen shots suck, at best. But here are two. One is of Tropic Thunder at a regular viewing distance and the other is very up close to the tv of a small pile of dirt. I'm using the split screen feature of the Darbee. And before you ask, I've unplugged the HDMI and bypassed the Darbee when I first got it to make sure it wasn't somehow giving a bad picture for comparison.
The Darblet increases detail (sharpness and contrast) without introducing bad artifacts, unless you turn it up way too high. I don't know what daisy chaining will do either, but after being proven wrong about 3D, I'm hesitant to dismiss any video improvement claim these days, specially one that has such rave reviews as the Darbee, until I see it for myself.
Again, everyone will have their own value set. I put a Darbee on my 70 and my 144. I will turn it off and back on again during a program just to continue to be wowed. I put it right up there with the difference between 480 and 720. Not kidding. YMMV.