Has anyone built a GP P-38 Profile?

Yes! It is an excellent flyer... BUT

Be sure to build the tail booms with light ply or thin plywood skins. I used the provided balsa skins and the booms cracked during the first flight (in the air). I made a hard landing after this first repair and both booms broke off. The tail feathers and the wing survived untouched, but the booms were completely shattered. If I had it to do over, I would use 1/16" ply on both sides of the boom. I was worried about the completed model being tail heavy if I beefed things up, but I ended up putting a few ounces of lead on the back of the stab. I have O.S. .25s on mine. It does fly very well and is a thing of beauty in the air. Be sure to break-in both engines well. There is nothing worse than one engine quitting on approach. Run them in until you think they are broken in, then do it over again the same amount. Like any heavier twin, keep 1/4 to 1/3 throttle until you cross the threshold of the runway, then reduce the throttle to let her settle in. It is better to land a little on the hot side than to have the plane drop out of the air 3 feet above the deck. Sneak up on the correct landing speed from the high side.

Tom