I haven't noticed a tremendous difference with mounting the tank on the inboard side of the fuselage; to the extent that I can tell a difference, it's better. You do have to adjust the engine a bit differently on the ground, as it richens up when it starts going (or at least leans out less). This is one of those "I haven't noticed much" things, because my usual approach to a first flight on an airframe is to aim for too rich, and then sneak up on the engine's happy spot on subsequent flights.
(Edit) The theory on the inboard tank setup is that because there's some head between the tank and the engine, it's actually pressurizing the fuel a little bit due to centrifugal force (or centripetal acceleration -- take your pick). That pressurization goes up with flight speed, so if you're adjusted a bit rich of high speed, slowing down leans you out and speeds you up, while speeding up richens you up and slows you down. I've only done this on pressure tank setups, but it certainly seems convincing -- and it makes finding a home for a tank on a short-nosed airplane much, much easier.