Are you looking to get the raid system on the Iwill, or no? If no, I'd go ahead and get the non "R" board. I hear its really unneccesary to have the redundant disk array for doing audio if you have 7200 rpm ata100 hard drives and cheap CDR disks to do the important backups ons. I've never had a track count problem with standard high quality drives.
I think the KK266 non-R version is right at $100 right now.