Remember, raider squads are not very comparable to warrior squads. If I could take a squad of ten warriors (out of the warrior squad unit) and put them in a raider, that could mean 3 "heavy" weapons, and two special weapons. However, raider squads can only have 1 heavy and 1 special (+ the raider's guns).
So: Have 5 man squads in raiders. One armed with a splinter cannon, or blaster. The raider can be upgraded to have a disintegrator (if you have a splinter cannon) or a horrorfex (if you have a blaster). Full squads of warriors on board I have not tried. How about a sybarite with a 'fex on board a raider with a 'fex. That is two pinning tests from a single vehicle (if mounted). Remember, the raider and the raider squad count as different units when shooting, so you wouldn't combine the terrorfex results.