Single Comment

The first move in a game of Chess isn't even CLOSE to the most important
one in a typical game.  If you look through the log of a decisive game, I
bet you will easily find at least one point where allowing the player who
eventually lost to take 2 moves in a row would EASILY have turned that loss
into a win (for example, maybe around the time the queens were
exchanged?).

I recall reading about a variant on this site where each player begins the
game with the right to make a double-move at one point of their choice
during the game.  The author suggested that forcing your opponent to use up
this ability was critical, having an equivalent material value of AT LEAST
queen + rook--almost two orders of magnitude above the 1/3 of a pawn we've
been assigning to the first-move advantage in this thread.

I also see no particular reason to think that a Bishop moving 7 squares has
equivalent value to taking 7 consecutive moves in a game of
checkers--but if it were true, that would seem to severely undermine your
theory that the first move in Chess is the most important one, since no
piece can move farther than 2 squares on the first turn.