The J frame S&W's usually have plenty enough spring strength to have the hammer spur bobbed without having ignition problems...unless some clown has done a home-boy action job and either cut springs or replaced them with lighter aftermarket ones. Any decent gunsmith or armorer can do this for you. If you decide to try it yourself, the hammer should be removed from the gun first.
I have owned several that I cut the spur on and have done it for many others. These are close range "Oh Shit!" guns (yes, I too, have shot them at 50yd. and know they are accurate, but that's not what they are "for") and the last thing you want is for it to go "click" instead fo "bang". Always leave full spring tension on these little guns.
Once cut, the gun is really a DA-only proposition since the way to cock the bobbed hammer is to "just" start the trigger squeeze slowly and use the tip of the thumb to then pull the top of the hammer back to the full cock position. This is something you must practice and even then it is not 100% reliable. Holsters that secure the gun by the trigger guard will work fine with the bobbed hammers.
My preference is for the 40 / 640 / 340 models as this is not an issue and the web of the hand can ride a little higher on the backstrap.