Anything faster than a standard SATA 2 SSD drive is not really noticeable on a desktop. The super fast drives are intended for very high server/database workloads where the transactional speed (the number of IOPS or IO per second) is the bottleneck.
http://en.wikipedia.org/wiki/IOPS
As per the above Wikipedia article, a 7200 RPM SATA disk has 75-100 IOPS, and a bog standard SSD has 60,000 IOPS -- that's 600x more random IO operations per second, on a cheap SSD. That is a MASSIVE increase in random IO speed, almost three orders of magnitude greater!
Now lets compare the cheap SSD with a RevoDrive 3 X2 (I don't know how many RevoDrive models there are, I'm just using the one in the Wikipedia article as an example). Cheap SSD: 60,000 IOPS, RevoDrive: 200,000 IOPS, which is "only" a 3.3x increase in speed.
The RevoDrive (and others like it) are amazing drives. However, they are designed for very specific purposes, and desktop use is not one of them -- a desktop will never be throwing 60,000 IOPS at a drive, let alone 200,000. It's like using a huge van to transport a handbag -- it does the job, but is massively over-speced. And as stated above, your boot times will increase greatly because of the additional time required to initialise the card. Also, very expensive. Cool to have, but not worth it as you won't perceive any gains from it.