I've also done three of these builds so far. Used the SC847A chassis with direct iPass cable access (i.e. no port multipliers), 4 drives per cable. Downside is you need 9x SFF-8087 connectors on controllers, and 9 iPass cables to somehow route. Don't get the SM iPass cables, TrendNet makes better ones. Upside is you have dedicated SAS2 bandwidth from the drive all the way though the controller and the PCIe bus. Likely overkill. Also a tip, you can mount 4x internal 2.5in or 2x 3.5in drives. SM has the part numbers for the brackets on the chassis' product page. Don't put anything you'd remotely want to hot swap in these brackets, they will be buried under the motherboard tray.
I've used 4x LSI Logic 9211-8i controllers plus the onboard of the SM X8DTH-6F. Both the onboard and the 9211-8i use the LSI 2008 chipset. I have Solaris and ZFS setting on top of these, so I don't have hardware raid.
This is actually very solid hardware so far. I had a PSU fail and thats it. Let me know if you have any questions.
