As stated prior, spinners work just fine on SATA2 with no performance degradation.This looks interesting:
2x SATA (6Gbps)
4x SATA (3Gbps)
8x SAS2 (6Gbps) via LSI 2308
Not sure if I like wasting 4 SATA ports for 3 Gbps.
Not sure how different the LSI is from HBA+LSI.
This might be a better board if I decide to go the dedicated NAS route.
The LSI controller is the same one used on many of their PCIe HBAs. It's just that, instead of being a separate card, it's integrated into the mainboard.
I use mine for a dedicated NAS, but there's no reason you can't do the virtualized NAS plan. Unless somehow a ceiling of 4 cores/8 threads and 32GB RAM are somehow too low.