Like Dave says, the snap-on reader is great.
For the Vec - no other reader understood the errors and would just return "misfire on cylinder 1,2,3,4" - most helpful fault ever!
The snap-on reader, with the VX personality module and CAN interface told me "crankshaft sensor - invalid signal"
I'd love to but a snap-on reader but, sadly, they're a little out of my budget :(