If you go the 4.7 route, you'll have the nice spin on filter. If you go the 5.7, you'll be stuck with the cartridge filter. Removing the skid is the only way to get to it, too, unless you take a plasma cutter to the skid where the filter is. I wouldn't recommend doing it since the filter is a little ways up there and it may weaken the skid (not that it's there for boulder protection, but you know what I mean). There's soon to be some other manufacturers for the filter. The stock Toyota design is high quality, not that its hard to put a paper filter in a circle and put 2 plastic rings on both sides of the filter
I'm hoping Toyota will redesign the filter to accomodate a spin on (not holding my breath though) so I can convert mine to a spin on.