If you have high minimum performance requirements (it must always be at least this fast), then go back to your SAN admin with that and discuss dedicated storage.

If you do end up using storage that's shared at the physical drive level, then there's zero benefit from splitting up files onto different logical drives.

I do recommend having a logical drive for the OS (typically C:) keeping your SQL data and logs off of it; this is primarily to keep filesystem level fragmentation to a minimum on the SQL drive, and make sure that you can run CHKDSK on one without having to also do the other. If you need to run CHKDSK, it's most likely going to need to be only on the OS (or, perhaps, on on a SQL file); but it operates at a logical drive letter level, so I like to separate those.