I'd recommend not using the WPPSI due to age/ceiling issues.
Our tester used the SB-V for DS when he was almost 5 1/2. I don't know if it's all tests or my tester's way, but she said the SB-V lets you bounce around. So when DS would get bored with a category but not finished, she'd move on and come back. She said it felt like it held the attention of really gifted kids better. Probably because of timed portions on the WISC that'd be difficult.
One other thing that you didn't ask for but I have to throw it out there is make sure your university is versed in gifted testing of YOUNG children. Our first testing experience was at our local university and they assured me they'd done many IQ tests both for gifted and special ed issues before. Wellll..... My 5 year old was the first kid under 10 our university student tester had ever seen. It went terribly, he came out crying and shaking. She told me that she knew he was NOT gifted (or anywhere close) and was pretty sure he'd need a special school, that he may not be able to mainstream.
Crazy student told DS about halfway thru that there were people behind the one-way mirror watching him. He totally FREAKED.
6 months later, different tester, different test and a much much better situation. And my HG+ kid mainstreamed just fine...
