PERSONALLY, i prefer shrouded, b/c i pocket carry a lot, and the hammer could snag...but, you can easily adapt your draw on a hammered J-frame by simply placing your thumb/web over the hammer during the draw and then dropping it to the side after it clears your pocket, so there is nothing wrong w/ an exposed hammer as long as you practice your draw (from wherever you carry)
moreover, i have no use for DA/SA as i do not fire any wheelgun in SA mode––its all DA/DAO for me––draw and press the trigger
––no cocking, etc, whether you are in a real fight, nor if you are going to practice for it as you should practice w/ your DA trigger press moreso––YMMV
now, some folks do prefer DA/SA, many claiming that its easier to make "harder" shots in SA (and to an extent it is, esp for some shooters, but then one can make similar shots in DA by simply learning the trigger on those), but like i said, in a fight, its very unlikely that you will ever get the chance to use cock the hammer back into SA.
ETA: i pocket carry J-frames, 642s