extra filter or fuel line isn't going to make the difference in winning and losing. sorry. I don't run an extra filter simply due to the fact that its another mechanical connection that could fail. but there is nothing wrong with doing it.
I also don't really see where races are won and lost on fuel mileage. In every race I have been too its very seldom the leader never crashes and one crash is a pit stop. I watch Tessman pit 730 almost everywhere he goes. I personally pit at 730 everywhere I race as well. I use Paul Kings advice in that you should pit 2 minutes less than your total runtime. an extra 5cc of fuel in a filter isn't going to take you 2 minutes to the next pit window.