I agree with Matt. The high pressure high flow system is one of the strengths of going with an alternate engine. Besides eliminating any possibility of vapor lock, it also provides protection against such malaties as water contamination and un-mixed 2-stroke oil.
The pluming is not particularly difficult, especially when compared to some of the options you are considering here. I just have a single return line that returns to the left tank, eliminating the need for a 2 control valves. That means that when I am on the right tank I am transferring fuel to the left which leaves open the possibility of overflow out the vent, but I always set a timer and it has not been a problem for me.
When fueling away from home, it is difficult to get the 2-stroke oil to mix well, even with rocking the plane. The high flow system mixes it quickly in the the left tank, but when I switch to the right I often get several seconds of rough running now matter how much I try to shake and shimmy first. If it were not for the high flow system, those several seconds of rough running would turn into nearly a full minute. That would be NO fun!!!
Glad to see you back at it Todd!
Trip report: I just flew my RV-6 up to Idaho for the eclipse. We stayed at a place with a private dirt strip in the Sawtooth Mountains at 5200'. Epic experience. Very hot sometimes and I was glad to have a return flow system.
Dave Leonard
Turbo Rotary RV-6
coming up on 1000 hrs soon.....