No, no, RAID 0 works pretty damned well actually when using SATA II instead of SATA III. The Crucial C300s work amazingly when used in the SATA II ports. They're backwards compatible with SATA II. They just don't work almost at all when used in the SATA III ports, let alone RAID which wasn't even an option in the RAID setup.
I already had sniffed out a bit about the SATA III issues with this board, and couldn't get a consensus on whether RAID was possible while using SATA III with the Crucials. However, I went with the C300s anyway on the hopes that a driver will improve things, or at the very least have a future proof option for future board with a better native SATA III support or a standalone controller.
My reasoning is this: When using the SATA II ports on this MB in RAID 0 the SandForce drives are actually faster than the C300's today. Plus they are about $125 cheaper. As far as future proofing is concerned, it seems unlikely that a driver update from Marvell will fix all the issues. More than likely a new chipset (probably from Intel) will be needed to take full advantage of SATA III. In addition the C300's themselves don't yet take full advantage of the SATA III speed. The next generation SandForce controllers are rumored to get closer to the 600 MB/s theoretical maximum of the bus. In other words it would take a full MB upgrade to do a good SATA III RAID 0 setup, and by that time much better SSD controller chips and much cheaper GB/$ ratio drives will be available.
What does everyone else think? Splurge on the C300's today or go with the trusty SandForce drives instead?