Efficiency
N256H often flies close to 1,000sm on standard tanks with reserves. With this plane you can go high and run LOP and really conserve. That is the way to get the best MPG, hence the best cost efficiency. Running this way, the backside and the bladder usually run out before the tanks do. The gatorade bottle does come into play also, but I don't know many ladies who want to use the lady-j adapter, especially with others beside possibly a husband in the plane. In 83+ flights, N256H has only twice not made it to destination without refueling because of 60+ mph headwinds.
If you want to fly low and fast, then tip-tanks would be my suggestion, although Van's is adamantly against them (as they are against any engine mods as well, including turbo-normalizing, which I would love to get some true performance numbers on).
Diesel may be an option in the future, but there are precious few diesels flying in GA to convince me that they are yet a viable option.
Another consideration is that with normal tanks, you can fill them, fill the seats, fill the baggage compartment and fly. There are very few planes you can say that about. Also, if the normal effect of tip tanks is true in the -10, the fuel in the tips may be considered to increase your useful load by that amount. I can't speak to the technical aspects of this, though.