I dont think speed matters, unless you jump straight to a SSD. the PS3 really doesnt benefit much from faster drives.
I recently plugged a WD5000LPVT into my console and it works exactly like the way slower 40GB model.
I think measurements from Df prove you otherwise though, showing a clear advantage to 7200rpm drives. If anything then while an SSD does provide a real benefit, it's not nearly as much as for a PC, so it's a relative waste.
I had some DF articles in mind, but apparently my memory aint the best. the verdicts seems to be that the lower latency of 7200prm drives/SSDs help a great deal, but faster transfer rates dont.
