While you may lose the "mono-block" design, the Stereomours will have the latest and best circuitry and possibly bigger/better output transformers (unless you did some big upgrading). I own a set of older Paramours and a pair of Paramounts. I don't have a Stereomour but I could see why it would be an upgrade over (especially stock) Paramours.
On the other hand, Paramour is one of the best named amps in the line. There's nothing like saying "Yeah, I have a couple of Paramours and I just love them."
Still, I've been eyeing the nice, neat design of the Stereomour. Maybe I will buy one someday and just call it my third Paramour.