I've got a cluster of R715s. Be advised that, last I was told, the H200 controller only exports one raid volume per set of physical disks, and does not do raid5. So you can't mirror a pair of 150gb 15k sas drives and make Proxmox see it as more than one drive. (in other words you can't split it into a 75gb sda and a 75gb sdb).
My old PE2650s w/ SCSI controllers could do that...so it is quite ridiculous...but I suppose that is the world we live in.