I've never tried the Rockwell or the Gentile razors. I love the Fatip Grande, however. It is slightly more efficient/aggressive than the Merkur 34C (my 1st and conceivably my all time favorite razor). When you tire of these razors/choices, try a vintage Gillette New LC or SC. It will blow your mind. And then... buy them all!!
I dont think saying buy both if you are concerned about the extra 20 to get the Rockwell is helpful. So I'd vote for the Rockwell. Its a fantastic razor. As was said. Its like butter. The plates are funto change up. Especially if I skip a day I can jump up a plate. I have the 34c and the ej89. They both never see the light of day now that I have the Rockwell.
I have a Rockwell 6c (2 of them actually) and would definitely recommend it. I haven't used another razor since I bought it except for my Gillette Tech that is in my travel kit. Rockwell makes a fantastic razor.