my suggestion sort of addresses this by making stunning fist last for the whole round and be moddable to the situation. It can make some blistering high save requirements for con by pummeling the same target generally at lvl 5 13-14 + 3-4. This "Higher chance" helps make up for the effect being only a single round transitory. Also it helps with cost efficiency against swarms by allowing you to potentially dish out 3-4 stuns on weaker mob swarms at a lower DC, but always 1 DC higher than the cleric which has a chance to propagate the stun indefinitely.
Its probably still not enough to truly balance this mechanic but it certainly helps and steps in the right direction.
