Given a rake structure of 10% up to $5, plus $2 for promos.

If the opponents were exactly the same and played exactly the same (relative to the blinds) all win rates would increase slightly, and winning players would see a larger increase. How much of an increase do you think that would be?

I'll answer this, but I'm going to lock it up.

First of all, it is about stack size, not blind size. If the 2/5 and 1/3 buyins are the same (say $500), the winrate of the best players will go up in the 1/3 game because they will play deeper than the 2/5 game. The deeper the game, the greater mistakes can be made with the same players.

What will happen is that the losing players will bust out faster. It is hard to say how much faster, although generally there are fewer deep stack tables than 100 BB tables in a given room.

Prior to the Moneymaker era, NLHE was rarely if ever spread. The reason is people was bust out so quickly that if a game opened, it just wouldn't last very long. If you read Brunson's SuperSystem, his NLHE section was for an uncapped buy in game. People would buy in for at least 400 BB. It is also why much of the advice given makes little sense in today's 100 BB world. I believe it was the Stratosphere that opened cash game NLHE at a limit of 100 BB around the time of Moneymaker win that made NLHE what it is today.