I carried a M36 3" for nearly twenty years, almost daily and liked it a lot. I found that the grip length, not necessarily the barrel length was the deciding factor in conceal-ability. I eventually bought a M60, in the same barrel length and found it equally good. I use an OWB holster of my own, open top design that's good throughout the year... a long t-shirt covers it adequately in summer and, of course, winter is no problem. IIRC, I've never had a hang-up from the hammer, while drawing...and yes, I cover the hammer with my thumb on the rare occasions when I pocket carry.
A J-frame's cylinder is just a bit thicker than a single stack 9mm auto's width, and I've found that if you can carry one, the other is just as concealable. The choice is really about the capacity of the 9mm and the gun's controls, (safety or not, magazine release, slide stop, and feeding); vs. the revolver's lower round count & simplicity (pull the trigger, if it goes click, pull the trigger again). For me, the simplicity is the factor, especially in the heat and confusion of a close in defensive encounter. I'll not denigrate those who choose an auto, as each of us must make that determination based on locality, training regimen, and personal physical characteristics.
As to the recoil issues with .357 ammunition, I've found that practice with a lighter load, to learn the gun, practice presentation techniques etc., works just fine. I carry Hornady 125 gr JHP's for SD use, practice with them from time to time and do just fine. Btw, I'm 70 yo now and use Skelton's old favorite .357 load for practice, (a 158 gr LSWC at 1150 fps). It's doable in a light, all steel J-frame, and does a nice job of emulating the SD load's recoil.
I live on a farm, here in KY and make daily trips to town, and I maintain and use a range, behind the barn just about every day...for that reason, I don't feel the need to go through 200-300 rounds for a good practice session. Two or three cylinders of loads do the trick nicely, and are not punishing even with full house .357's. For those that need to use a public range, once a month, a higher round count is necessary to cover all defensive drills, and that would punish even the most hardened of shooting hands.
All in all, the .357 is a good choice for defensive use, and the Smith J-frame a fine choice on its own. A heavier gun (don't know if Ruger's offering is heavier but suspect that it is), is a bigger drag on the belt, but would make practice sessions with higher round counts more comfortable.
HTH's Rod