Quite interesting, what about trim support ? As far as i understand, vmware doesnt support trim. And rely on gc those days is also over. Since more and more os's support trim, the gc is less aggressive as it was before. We tested ssd in vm environment, and with heavy load and ssds that where filling up, major gaps in performance kicks in. Even so badly that a sas array would cycle around the ssd... With two fingers in its nose...There is another option that I very highly recommend: Dump the 15K SAS drives and use one or more large SATA SSDs instead. Even a single SSD will out-perform a pile of SAS drives in a virtualization scenario. For my c6100 VM cluster, I use 512GB SSD drives to house my VMs, and I run up to 12 big fat Windows VMs per c6100 node without any noticeable slowness. I could very likely run many more. As you probably know, VM IO is usually limited by disk IOPS, and even really fast SAS drives will give you only ~200 IOPS while you gets tens of thousands of IOPS from even the worst SSD drives.
Here is another idea, since the c6100 has only three or six disk slots per node: I have stopped using any type of RAID for VM storage. Instead, I use simple SSD drives and rely on very frequent VM replication plus daily backups as my DR strategy. This decreases storage costs with only a small decrease in possible downtime and very small data loss window, which is perfectly acceptable for most (but not all) VMs. My c6100 "corporation in a box" setup has three c6100 nodes acting as VM hosts plus one one as a VM replica destination.
I must say, last time i tested and spent time on it is a while ago. We tested with intel modular server en promise vtrak storage.