Yep, that is our next plan, but also have problems with the GBE Nics on this machines as well (1% sustained throughput....) yet the hdparm output is 350MB/s, plus it is also "sort of in use.. by the client" so they don't want us to touch it unless we are sure of a fix.
I'd rather not use the onboard, as one of the reasons for this config was to include the separate cards for DRP, ie technically we could switch the card/drives to another box and bring the array back up.....

Rgds Ben