How many pools to support different workloads?

I have a (not so) theoretical question.  If there were an existing SAN with 40% RAID10 and 60% RAID5 SGs, and we were replacing it with a new VNX.  Would we be better served by combining all of the storage into one large RAID5 (4+1) FAST enabled pool (5 EFD, 30 SAS, 30 NLSAS)?  Or carving it into two smaller pools and with one being RAID-5 and one RAID-10?  The IOPS are ~ comparable to the 40/60 split of the capacity.  I am concerned about having small pools.

The VNX, with one large RAID5 pool, has the IOPS to support the total required (even with the additional write penalty of RAID-5).  So the question is really, do we want to mix workloads in a single pool?