I think it'll work ok. It will tend to hurt PCs and help monsters, especially at higher level. In particular it will make larger PC groups relatively less powerful and lessen the quadratic buff effect.
Personally I agree with others that stacking bonuses usually isn't really an issue in 5e because of the Concentration mechanic and because powerful monsters get very high to-hit bonuses, and often do enormous damage on a critical hit.
In my Saturday game the dwarven forgepriest Cleric-8 has AC 25 (+1 plate, +2 shield, +1 forge bonus, +1 ring or cloak bonus) so most foes are only hitting on a 20, maybe an 18. He still got taken to single digit hp by a single crit from a wraith.
I suppose even without magical stacking, they would still have AC23 which is still awesome.