If both have the same instruction sets, and BIOSes are configured with same features enabled (VT/AMD-V, NX/XD, etc), they *should* work. Anyway if servers are in place, you can test them first with a single VM and just vmotion it from one to other and also vmotion it back to check if they are compatible. If vCenter throws you an error, enable EVC BEFORE starting to deploy production VMs.