Stick with 5400 rpm. Higher speed drives will work, but due to the limited power supply on a PS3 (especially the slims) they tend to burn out faster. I always warn my customers against putting drives over 5400 rpm in their system, but they do it themselves anyway. 9/10 return within about a year with a dead or dying hard drive and an "I wish I'd have listened" look on their face.
Play it safe, don't push the system to hard with a high powered drive.