mikeh, on 2012-March-15, 15:01, said:
If I were to switch, it has to be to a club. Put yourself in declarer's shoes with, say, AQ Q109x AKQJx xx....while we should play N for a stiff heart, ducking a club spells disaster if N has another heart to lead back. Meanwhile, we appear likely to have 9 winners by rising and hooking the spade. Now S wins and leads the club Q...simultaneously establishing the club J and breaking up any hope of a squeeze. Now, declarer, in addition to figuring out the heart situation, might well work out the club suit, whether you switch to the 9 or the x...I mean, why lead the suit? But I would put the chances of a spade switch working as close to zero. I also wouldn't worry about whether they make overtricks. I don't care if this is imps or mps.....if they have 9 tricks, we are getting a bad result, and maybe so bad that any extra 200 their way will make little difference.
My own take is that I find it slightly more credible that opener has AQ 109x AKQJxx xx and decided that he'd take his medicine in 3N rather than be doubled in 4♦.
We like Mike yet again! Excellent explanation, and you too, wyman. I am fully prepared to be wrong about my spade switch on this hand.