Didn't Smith recall one of these or is that another model that I'm thinking about?
"The weight isn't a big issue since i'd use an OWB holster. What I am not sure I'd like about an N frame is the bigger cylinder, but in reality, it's probably not much bigger around. Would a 3' N frame be less $$?"
N_itis answered your Q on the frame size. If weight was an issue I'd still go with the magnum. One more round and a more versatile revolver/round IMO. Can shoot mild .44's through it and the extra weight keeps recoil down. Prices are close and maybe a little lower on the magnums. All the 3" revolvers keep going up in price. They are handy, handsome and very accurate for a snubbie.
I'd like to have a 3" prelock 696 for the collection but am afraid it wouldn't get shot much as I would have another round to load for as ammo is not readily available and not cheap unless you plan on reloading.
As far as the diameter size of the cylinder goes I can hide a 3" 657 all day undetected with no problem, both OWB and IWB. Just need a good holster and a really good belt, plus a good Coulmbia Guide shirt to cover it up.