Only balance change I'd push for on Limpet is to give it old submarine float toggle(Current subs also need this), since it's amph unit it's expected to fight hovers and ships, being a seafloor crawler makes it essentially useless against those 2 factories in naval warfare.
Otherwise it needs no other changes, it performs great and unlike mentioned Snitch does not chain explode, meaning you can do a very lethal, flea like bum rush, the slow damage practically cripples anything in range allowing for more Limpets from the rear to push in closer.
Speaking when they work as counters is best used against shieldballs that are defended against Snitches(w or w/o cloak), since they have enough HP to handle outlaws and wreak absolute havoc with their slow once they get inside Aspis shield range.
They also perform godly as transport bombs, they got both enough HP to handle little AA fire that misses the transport and hits them(unlike Snitch) and since they don't chain explode they're almost guaranteed to hit the target.
Limpets are pretty much the best jack-of-all-trades suicide unit in the game.
