Would you play or defend this deal 3NT by south. Say, on a small H lead

I sat south, and stuck my neck out in the bidding shown after N bid 3Diamonds. I figured I had their suits "stopped".

First conside what you might lead, and analyze play or defend.

Next, and this makes it a five star difficulty problem, move to the E seat. You have to envision South's problems at trick 1. What do you play?

Declarer is going to play on diamonds and partner is going to get in. You dont get to put a spade through declarer. On the other hand, if declarer has S:Kxx and IF he has H:KJ tight, holding off the queen might give him 2 tricks in hearts but no third! ie. if he holds CAxxxx he can come to 5 diamonds FOUR hearts, and partner cannot wreak much havoc when in with the DA, even if he (as he likely does) holds the Club King. Most likekly he will shift to a spade, hoping, but that is trick 11 for declarer, with ONE SPADE KING and CLUB ACE.

But it takes 20/20 vision to imagine Declarer's actual holding and fate if you duck the HQ, with that vital East hand entry lurking and source of tricks in all suits (OK he can force 5 diamonds and H:K and over take HJ with HA and CA but that is only eight tricks in all.