I am going to try to test SIL with a pair of WD 250 GB over the next several days and will let you know. I have been trying to get a hold of the IT from SI, so far unsuccessfully. I emailed someone else, and hopefully they'll get back to me.
Calling Sil is of no use, please stop doing that, they just supply the chip and Bios-rom-add-on.
The only one that can do anything towards Sil is MSI, MSI is producing the board and release BIOSses not Sil.
For your information, I have reported this problem to MSI, and trust me, it's reported to people way up in MSI.
But as these people are very busy, it can take a while before I get an answer of some kind.