Posted 2012-September-13, 01:06
Small sample size, but...
In the last 30 days, GIB has 19 times been on lead against my small slam holding an A (excluding those times when GIB held AK). Of those 19 hands, GIB led his A 9 times, led a different suit 9 times and underled the A once (against 6N).
But, of course, then we'd want to know how often GIB underleads Q to determine which is more likely...
Over the same 30 days, GIB 14 times led against my small slam holding a Q (without A, K or J in the suit) and once he led that Q, 8 times he led a different suit, and 5 times he underled the Q. (Once of the 5 he was leading his partner's bid suit.)
So, it appears that GIB is more likely to underlead a Q against 6 than to underlead an A.