dwar0123, on 2012-March-19, 19:44, said:
- qjxxx kqjxx jxx
for 4 spades to go down 1 and 3nt to make, a carefully constructed hand where all the honor positions are one less then partners length in the suits. I would wager the odds of this happening are an order of magnitude less then the number of hands you could construct that 4♠ makes and 3nt doesn't. Maybe 2 orders of magnitude.
That is the only difference worth looking at, as we can ignore the vast majority of hands were neither can make or both can make.
Or you might have 9 tricks, and on the wrong lead, you get all of them in 3N, but you can't ever get a 10th -- even in spades. So I'm saying that opener should really only be bidding 4S with a hand that he hasn't fully described. And this means that responder is allowed to raise on a hand like this.