Big Pot Rake and the Cap Limit

Ok, so was reading someones' thoughts on playing heads up NL and they play higher stakes due to the rake cap. Now, I had never considered this, and obv since heads up pots are so large on average it is certainly very wise to play higher limits so the rake does not crush your edge. I drew up a graph for big pots (defined as two buy-ins) and the rake imposed on these pots. At micro (10NL and 20NL) - and if we include rakeback - the rake in these big pots is 3.5%. Higher than this it diminishes quite quickly - 50NL is 2%, 100NL is 1% and then the graph gradually curves towards zero. This is all due to the cap on rake taken from pots. So there are good reasons to play at a higher limit. The 100NL deal looks the best to me, but I don't think those games will be within my reach for a long time yet. However I could possibly bankroll myself for 50NL by the middle of next year so that should be my target, getting the best of both bankroll safety and paying less rake on average.