Tom, I have owned all of the projectors you mentioned, except the 3000e, which I only had for a weekend. I still own the Sharp and JVC, so those are my best comparisons.
I really loved the old C3X, and the only thing that made me give it up was the relatively poor on/off CR. I also felt the timing was right, since everything was going 1080, and I knew that eventually Sim2 would come out with a 1080 version. The 3000e was a very nice projector, very clean, but for me, RBE was too noticeable, because of the extra brightness, and the on/off CR, left me wanting more.
I have posted my comparison between the RS1 and Sharp, both of which I like, for different reasons. The high ANSI and color accuracy of the Sharp, and the High CR, and relaxing image of the RS1, since I am bothered by RBE. The CR difference between the Sharp and RS1 is minimal, perhaps more obvious on the new RS2, but I don't have that one....yet.
In comes the C3X1080, and it takes the best of the 3000e, Sharp 20K, the RS1, and the C3X 720, puts them in the oven, and comes out with an almost perfect soufflé.
Although the on/off CR could be a hair better, it is very close to the Sharp and RS1, and only noticeable on the very darkest, fades to black. Everything else about this projector is phenomenal. The image is rock solid, reasonably bright, even for larger screens, certainly brighter than the RS1, and way, way brighter than the Sharp. The fact that it is so bright, is a strong testament to how difficult it must have been to get the CR up there.
The only real downside that I have been seeing, is that it is somewhat painful to go from really good HD material, to SD. Part of it is due, I think to the brightness revealing more noise, softness, and imperfections, and part, I think, is because the performance is so high, good source material is no longer limited by the projector, so the gap between SD, and HD seems a lot greater.
Overall, I think this one is a keeper.