Maximum PC did a test a few years back showing that hard drive speed had very little effect on game load times, even using your specific configuration (2x74GB Raptors) vs a standard single 7200RPM drive. The bottleneck is almost entirely CPU-related, as most of the work is decompressing various assets into memory. Of course, a dead-slow 5400RPM drive with a small cache will hinder performance, as will slow system memory, but a faster CPU definitively improves performance everywhere, in-game and out.
Also, you'll get the biggest bump from this patch if you're running 2GB+ of RAM. Load times improved on my X2 3800+/1GB/RAID0 setup, but even more so on my Core 2 Duo 2.2/2GB/5400RPM laptop. Seems like they've basically added/fixed asset allocation, for example, entering a house and then backing out to the area map has seen the biggest improvement, along with loading save games in the same map.
I'll get back into this game at some point, but I ran into a random game-stopping bug (Leuvaarden didn't sell me the sephirot, and another quest killed the dialog...checked inventories and the monolith, no love, so I'm stuck). I was getting a bit bored with it anyways, so it'll be collecting dust for a while. This is why I think every RPG needs a console, as it would save me here and has saved me before, in Morrowind and other games.