rjs:
We too had problems with GWIA SP1, especially when we had Dual Processors on a Dell Server. It would peg out the utilization on one of the processors. It has been too long, but I think it locked up the server as well, but never abended.
We used the GWIA beta FTF (6.02g??)and turned off the second Processor, and it has been running well since.
I am glad to hear that it seems to address that GWIA problem for your clients, and it gives me hope for Service Packs again.