My servo setup is rather cumbersome. I have the Left wing on CH 5 & 6, and the Right wing on CH 1 and 8 (or is it 7?). The Elevators are on CH 2 & 7 (or 8, I don't recall which). I think that you can master / slave the channel so that the wing servos will function as a unison, but I haven't quite figured it out yet. It's setup ok now, and really the only mix I typically use is one to neutralize the roll / pitch on KE anyway. I find that I need about 15% Rudder / Aileron mix to take out the roll coupling. Everything is plugged into my Futaba PCM receiver. No powerbox used here. I didn't have any issue with power, responsiveness, and glitch, so I haven't had the itch to upgrade to a powerbox. I suppose, however, a powerbox will make setup more convenient. I think using a Y Harness with a programed Hitec servo will be just fine (Just use two and use the flapperon mix on the radio). I would if I have the time to do it, but once you've got everything kind of set up already, laziness kicks in .

The transition from glow to gas will be pretty easy. I would say the most important thing moving to larger aircraft is to grease your landing. You have a larger mass, and so stall from 2 feet will take a harder toll on the airframe. On the other hand, greasing your landing will be easier, as your preceived speed of the aircraft will be slower. Just keep applying power until your wheels are ready to touch down.

If you haven't put everything together my advice is to just build it stock (except for the horns on the elevators and rudder. I think the stock is too flimsy for my taste. I switched it to the H9 rocket city-style horns (because that's what I had). I would first mount the engine, and all the servos EXCEPT for the rudder. Do that last. That way, you will have the flexibility of doing it pull pull or just put it in the rear to get just the right balance.

I would personally avoid the CF stuff first. They are lighter, but will also break on hard landing. Alum will just bend some. I would just build it, fly it, then switch to CF if you're still not satisfied with what you got. If you do go the CF route, you probably will be able to bring the weight down to 17.5 lbs.

As for the engine, I heard the EVO 58 is a real powerhouse. Just make sure you don't break it in the stand. All gas engines are meant to be broken in while flying. Just use the suggested prop and proper break in, start up procedure and you really shouldnt' have any problem. You will definitely like the power of that engine, since it's reported that it can even haul a 33% aerobats (that's typically powered by 80 cc engine).