A Remarkable Disparity

A 7 6 5
K Q J 5 4 3
K
Q 5
J 3 10 9 2
A 9 7 2
9 7 6 3 2 Q 10 8 5 4
J 4 3 2 10 9 6
K Q 8 4
10 8 6
A J
A K 8 7 Contract: 6 spades, 6 no

Just a few days after coming across what must have been the most horrendous loss of matchpoints for neglecting to pick up an overtrick (from 70% down to 11!), I came across one of the largest disparities between a major suit slam and no trump. The former got 58%, the latter 94%, a spread of more than 36 points (with the decimals thrown in). That's expensive, I would say.
Further, lurking in the shadows, not to surface here but which could easily have been the case, were two other dangers of the trump contract when no trump is cold. First is a 4-1 trump break, not too unusual an occurrence when missing the J 10 9. You will note that declarer could live with that break and get 9 winners elsewhere in no trump. Secondly, you have a 9-card suit missing the ace. The favored split here is 3-1, which, uh, could have been deadly. Nuff said?

I believe I posted 4 reasons why no trump slams are so often more profitable than trump slams (when you have all suits stopped with high cards, of course). One of them exhibits itself in spades here, namely the 10-point advantage in a matchpoint event. Two are waiting in the wings, so to speak, as just mentioned in the last paragraph: the possibility of a bad split in your chosen trump suit and the potential for a quick ruff. Incidentally, if a 3-1 heart split could have been fatal in a spade contract, so could a 4-1 in a heart contract. That would depend on a few factors, such as whether the defender out of spades after trick 1 (and of course that suit must be found for opening lead) has the ace of hearts or his partner does. The fourth reason was that in no trump you can cash winners in any order you choose, which isn't the case in a trump contract. The most obvious example of this is a singleton opposite A K Q x x x, and no outside entry to dummy. And that is the suit led for openers.
That last-named occasional advantage isn't a factor here. Still, one advantage is glaringly manifested, and two could easily have been important factors on the North-South cards. 'Nuff said?