770 to 824 migration? my condolences to your customer.
Once again - if you have SRIOV capable adapters, don't make SEAs. You will have worse performance. Learn what SRIOV is, Virtual Functions and VNICs are.
You don't have to trust me, you can read e.g. this guy -
A first look at SRIOV vNIC adapters | chmod666 AIX blog. Benoit (the guy) is the co-author of the PowerVC redbooks and manages quite a big infrastructure.
I unfortunately can't give you information on performance tests of SR-IOV adapters, I received from another guy, who made the tests for IBM labs. I spoke to him last year, as IBM still didn't announce VNIC feature, and he convinced me, that SR-IOV performance is better, then of SEA. IBM uses the results to convince customers to buy SR-IOV adapters, but if you already bought them and paid money, use them!