This may not be a deal breaker but...

One thing you might want to bear in mind is that most if not all onboard raid controllers only tend to feature just a couple of channels.

I'm not quite sure I understand your raid0 setup (it's early morning, everything is all blurry :P) but if you were looking to get maximum scaling bandwidth out of the raid0 drives then you will need a pci express raid card as most onboard raid chipsets only have two channels. Four channel cards tend to be rather expensive, I'd hate to think how much the next iteration (6 or 8 channel?) would cost. You could of course just split the drives between the two channels most motherboard raid chipsets now sport, resulting in roughly double the bandwidth of running the drives in ide mode.

FYI I run two OCZ V2 64GB SSDs in raid0 and have benched raid array read performance at 280MB/s across the majority of file sizes (this is considerably better than an identical array using raptor disks). Four slaves run off one copy of wow and the main runs off a seperate copy. This is on a core i7 920/6GB.