I don't own either, and probably never will, but I think the convenience of being able to purchase filters elsewhere is a big plus for the FASS IMHO. The fuel splashing back while fueling with the truck running is a moot point IMHO, it is a convenience of one over the other and has nothing to do with how well either unit functions. If I were shopping, the longer warranty would definitely be a factor to consider. I don't imagine that someone would notice any difference in function from one over the other so either would serve the purpose just as well IMHO.