axb1=N might seduce your opponent to refrain from recapturing the newly promoted piece. Which in effect wins you 2 points instead of losing 1.
MISTAKE - Much better was 40... axb1=N
Sort:
Put a diagram here.
ha ha, that's really funny, I guess there is no difference, both queen and knight would be taken. 
It's an analysis of a completed game.
DC-poc wrote:
The computer analyst can talk utter crap at times.
In this game.
It marked my last move as a mistake.
28. gxf3? (10.04) WHITE WINS - Play might have continued...
The superior move was.
BEST MOVE (10.19) [Rab1]
Of course!
But alas, not according to fritz 12.
22. .. Nxf5 was pretty much self destructive. What was Fritz evaluation for it?
My move: ... axb1=Q
Computer analysis reckons it was a mistake and I should've promoted to a knight.
Next move in either case?
Qxb1 :-)
I guess the idea is that on the next move, I only lose a knight instead of a whole queen...