The other issue is figuring out what performance problems you're having with your empeg. I mean, sure, ReiserFS may increase filesystem performance and free up some IO wait or something, but what are you going to use that extra CPU time or IO throughput for? So far, I don't think anyone has encountered a dearth of CPU time, even running multiple third-party apps. The problem is much more related to physical RAM. So I'm not sure what you'd gain.

That being said, I'll never touch ReiserFS again after it decided to zero out a large portion of the files I had under it. Absolutely ruined a Linux installation.