In a K frame Smith, a 5" would be the cat's meow IMHO. For the most part, I prefer the 4" bbl's on my M19 & M66 Smith's, but...and this is a big but....that extra inch of bbl. does make the gun that much harder to conceal under a shirt tail or jacket unless you can handle a high rise holster.
My 5" bbl'd revolvers are a 629 & a M27 Smith. Both are "N" frames: better than a "K" frame for absorbing recoil, but paying for that benefit with the extra weight on the gun belt. I make my own holsters, (and it's hard to find one for a 5" bbl. BTW), and that add'l inch requires a very high rise to be comfortable when seated in any modern conveyance. I do like their greater sight distance, and balance, but object to the add'l weight.
All things considered, I'd buy a new 5" bbl'd Smith "K" frame M19 or 66 in a heartbeat if it was offered w/o the infernal lock...but I'm not holding my breath on that one. I do have a M69 in .44 Magnum, keep it loaded with Skelton's famous load, and really like it's "K" frame weight on the belt. It's a 4-1/4" bbl'd proposition that's been very accurate with my loads, and would be a nice back up gun to a rifle on elk trips etc., where a 2nd gun is a good/excellent idea. It balances better than either my M27 or 629.
YMMv, Rod