I've not seen the possibility discussed, but I was thinking that to even the board for the experts a pair or two handicap while playing tournament rules might be enough to do it- as Gary has mentioned in tournament rules white must generally sacrifice a pair to get to a winning line, and I've noticed that the game reaches a certain point of tension when one player has three captures. Perhaps a way to explore this option would be to analyse games between top players to see what percentage of white's wins were made when black had 4,3,2,1 and 0 captures and then see how the lines might be affected by giving black 1 or 2 pairs to begin.
Just a thought- I wonder if that would be the consensus among expert players or not? Also what about a pair handicap without opening restrictions on player 1?