I think as a sneak attack only being effective (i.e you must be undetected for it to work effectively) would be a good implementation. Then just really shite at all other times. That way you won't get hack'n'slash going on.
I think a workaround is important, but persistency is so important. There are only 6 local servers for me, which are almost ALWAYS full. If I were restricted to my shit on ONE of those servers, I would never have it. Persistency is great.