I cannot imagine passing with South's hand - Dbl is perfect. What's there not to like? We have AAK, a decent suit and most importantly we have short hearts (Having Axx of spades [3 of them rather than 4] is a very minor factor for me, the most important is to act with shortage). I don't expect partner to be acting every time he has 3-4 hearts and some balanced 12 counts or w/e. Now over 4H, North has a decent hand but doesn't have a clear bid. I haven't talked with my partner what direct 5S vs. 4NT (2 places) then bid 5S would mean. After 5H and X, I think South has a clear pass with no extras and see what North is on about and if he still asks me to pick a suit (?), I obviously then would bid 6D.