I have 2 J-frames with the internal lock. In each, one of the first things I did upon taking custody of it was to carefully remove the sideplate, mainspring and hammer and get rid of the piece with the locking lug on it.
I chose this option (as opposed to grinding off the lug and leaving the piece in) only after carefully examining what I could see of the lock's mechanism and satisfying myself that the absence of this part should not result in any mechanical problems--that is, that it didn't serve any purpose besides being able to engage the slot in the hammer.
What I do dislike is that there are still parts in there ( the locking cam, the cam spring, the shaft, etc.) that do not contribute to the gun's function. Ideally, I'd like to get rid of everything that doesn't help the gun go bang and just be left with holes and milled-out places in the frame.
But these last parts are somewhat inaccessible and do not seem to want to budge. As long as they stay put and don't vibrate out of place or anything, things should be fine. I actually don't have much fear of this happening, because it looks like the remaining parts, all of which are much smaller than the "flag" that I took out, have little enough moment of inertia so that recoil wouldn't tend to shake them up too much. I hope, anyway. Could anybody comment on this last observation, either agree or disagree?
Although the round count of both these guns is not high (<500 rounds) there have been no problems since the lock removal.