Well, I'm not gonna deny that doing this requires some serious playing around with terminal, which is not for everyone. While all this is nearly automatic in windows, macs are entirely different beasts, and I learned a lot about them doing this.
As far as performance-gains go, I'm using the 12" ibook, so... I was trying something that hopefully would make it a little faster. I do think it is, especially in the boot-up.. but I didn't measure, nor would I know how to.
The real gain for me was, as I said, not the speed-gains, but the fact that I don't have to worry so much about losing vital files, as they are all stored on different partitions (as well as a backup-drive).