From my perspective of gaming (FPS, RTS, MMO), graphics design and software development:
I've tried dozens of gaming and mechanical keyboards (Deck, TT, IBM, every one Logitech has ever made, Microsoft) and my favorite, by far, is the Corsair K90. Looks slick, built like a tank, great key press...
Upgraded from a 920 @ 4ghz on a P6X58D Premium to a 3770K @ 4.5ghz on a Z77 Sabertooth. About the same temps. It's a solid boost, but not monumental.
I could've been happy with my 920 D0, but it was rebuild time. Really looking forward to Haswell.
You're right. As long as you keep in mind that manufacturers upsell their specifications, you can at least have the right expectations.
I think it's less about the specs and more about the experience - you can try a pair of both and use the extras for case fans, if you want to be absolutely...
I tried 100 CFM vs 70 CFM on the H100 and only noticed a 1-2c difference. It really is quite thin, if you've ever seen the radiator.
The sound level of the Cougar Vortex is 17.9 dBA whereas the one you linked is 37 dBA.
If your case is out of the way, or you're not sensitive to fan noise, then...
Had the same decision to make and ended up going with the H100. As Rylan said, the H100 is pretty thin, so you wouldn't gain much with 3000 RPM fans.
I replaced the stock fans with Cougar Vortexes, which have been excellent:
Been pretty happy with my 3770K, coming from an i7 920 @ 4ghz. Not a massive upgrade, but a good one. Waiting for Haswell...
3770K @ 4.5ghz, 1.21v using Corsair H100. Other specs in sig.
Might be able to get the voltage a bit lower, but I'm satisfied so far.