I've got two Ninja 2's and I have been extremely happy with them. One of them is run on an AM2+ which already has a backplate and decent mounting stock. I do not run a fan on it, however, it is ducted to the rear fan. While inclosed in a desk behind a door, I don't think I ever got it over 50C on a Phenom x3 8450.
My second computer is a Q9300 OC'd to 3Ghz with the Ninja 2 and a Xigmatek bolt-thru kit. With all the fans in the P180B set to low (door closed), I top out at 55C.
I used to have a TRUE and it did cool well, but it required a noisy fan to do so. Because I have had such good luck with a Minja in a 3rd build, I thought I'd give the Ninja 2 a shot and got rid of the TRUE. I plan to make a support bracket for this as I did with the TRUE I had too.
With that said, I think that with proper mounting, this cooler is probably every bit as good as the original Ninja (revision B or whatever).