A propos ...
If you follow the rook exchange lines (given above) after 2.Kg6 and 2.Kf6 through to 4.Rxb4 axb4, these positions are what you get:
5.a5 Kc4 6.a6 b3 7.a7 b2 8.a8=Q b1=Q che--
Well, it's check in Diag 3, non-check in Diag 4.
Dvorjetsky refers to the 'check' queen ending as drawn - as it may well be. One infers, of course, that the latter - 'non-check - Queen ending is a win for White.
I'll tell you what, though: neither is a gimme!
Take the 'Check' line. After 9.Kg7 Qb2ch 10.Kg8, Black has no useful checks, which indicates he will have to look for some other way of discommoding White.
In the 'non-check' line, after, say, 9.Qc6ch. Black does have to watch where he places his king in order to avoid the exchange of Queens, or worse, having his Queen skewered for nothing. As it transpires, White cannot force such an exchange (or win of the Black Queen) from the diagram position.
In both games, The White pawn has to be guided home, with the WK running a gauntlet of checks. In some lines, Black's King does well to keep right out of the way - retire to the a-file withal - and let his consort get on with bombarding the enemy king with checks.
Despite the considerable situational differences at the outset of the Queen endings, it is hard to see that if one is a draw, the other is not; or that if one is a win, the other is not.
Thoughts and ideas?