NH!
The first thing you should think about is whether RHO psyched
(well, that's what I'd be thinking!). You've got a 20-count and
even if RHO has 12, there's only 8 left in the deck, so you know
partner isn't balancing and if you pass here, LHO might even
pass since he's going to have less than a five-count on average.
If opponents play a 1 NT as forcing (say they play 2/1), you
could be better off doubling since your opponents may find a
better spot than 1
.
Also, if you double with the intention of rebidding 2NT, what
are the chances that partner will raise you to 3NT? (Not very
likely, unless RHO psyched!) Sure, it will be nice to hear a 3
call
by partner, but that isn't too likely either. Also, if you happen to
end up in 3NT, where's your source of tricks?
In matchpoints, because of the vulnerability, I think you've got
an easy pass. Sure, you could miss game if partner has hearts
or a diamond suit but you could also be +100/+200 on this board
if you pass; at matchpoints, frequency matters more so I'd be
more inclined to pass and get my finger or mouse on the A/K
.
At IMPs, I'd be more inclined to double and bid NT at the next
level since it could be that RHO psyched and there is a slim
chance of a game. Still, at IMPs, if my partner passed here with
this big hand, I could at least understand his thinking.