I'm often the opposing view on ProFlexes - as cool as the Vectors look, they feel like a death-trap to ride IMHO. I also didn't like the feel of that rear suspension compared to the FSR - the pogoing was awful on the ones I rode.
Replacements for the rear air shocks in those FSR dimensions are cheap, but sourcing bushings to mount them can be a pain. Those old SIDs are dead simple to service and although they're flexy by today's standards, they still feel miles better than Vectors (he says, dawning his flame suit).