Thank you for the Paul Randall blog - it will be helpful.
I tested a new SAN by running SQLIO every hour from a VM server for several months, and looked at the IOPS change over time as more systems were moved to it. I'm looking to do something similar, by disk drive, on the new server. I might want to move my TEMPDB, or split the SS12 database between drives if I can show improved performance.
On the other hand, I am reluctant to change a system to solve a problem I don't have. This new HP DL380 is giving me over 110,000 IOPS from SAS drives in RAID-1 configuration, and has plenty of memory and CPU.