Undoubtedly true, hence why I added the proviso "major" when talking about bottlenecking - I'm sure poor 2D hardware will have an effect as well as raw I/O & CPU grunt
Rather than break my desktop Raid0 config and spend ages backing up and restoring it afterwards I set up a Ramdisk on the Revo, and ran my XBMC install from that instead.
Aeon performance was a little better than from the 2.5" HDD, but not perfection, like the desktop machine.
It looks like the I/O speed from storage is almost at the point of no further benefit when increased - going from USB to HDD was very noticeable, HDD to ramdisk not so much - so I don't think I'll bother putting in a proper SATA SSD to replace the 5400rpm HD.
Any further performance is going to have to come from CPU & GPU.
As far as clocking the Revo - I don't think I'll bother with that either. It runs very hot even at stock speeds, and I don't really want to fry it for the sake of a bit smoother Aeon UI
I guess I am prepared to live with the thing being a little laggy compared to an ultimate hardware rig, considering the price of the Revo (and the fact I mostly stay with Ronie's Transparency skin rather than Aeon/Hitcher/Showmix).
To me the smootheness difference isn't worth the extra hassle. You must have a bigger perfectionist streak than me :p