You didn't mention whether you're doing L2 or L3 via the 3750s. L3 is controlled by just one elected stack member, failure of such an active master might cause one of the slowest recoveries, but likely any stack member loss might cause some interruption.
If all ports on the stacked switches are multi-homed to all the connected hosts, there might be advantages breaking the stack. For instance, not having the switches have to contend with all the traffic placed on the stack ring (according to the improvements made on the 3750-E, the original 3750 puts all traffic going across the member switch on the ring).
