My son doesn't have Asperger's or any learning disabilities. He got on the Rias at age 6: 177 non-verbal (hit the ceiling), 143 verbal, and >160 FSIQ. He got all the way to the end of the non-verbal, which is normed for adults up to age 94. That correlated with his Raven's matrix score of 99.1%.
The RIAS is shorter than the WISC and doesn't have the speed-type tests. There are quite a few articles showing that the two tests have predictive value/overlap with each other.