On the SB5, DS got a FSIQ of >140. On the WISC IV, he got a FSIQ of 129 (!) (with a GAI of >145). He found the SB5 more engaging, especially the working memory subtests (which he ceilinged on the SB5 and got under 100 on the WISC). Not sure what that all means, but that is what I have to offer in the way of comparison. FWIW DS was pretty old when he took both tests, so ceilings were an issue.