I dislike dretch punting. With it, if there are 2+ dretches piled behind me, I can't move. With dretch punting off, I can at least kill them. Also, I have seen more accidental tking with dretch punting on than with it off. Someone will see a dretch in the middle of a room, figure it's just in the way, attack it just as it's evolving, and kill it.
With dretch punting off, aliens think twice before attacking dretches.