Going to Lithium power source is great (all of my planes have LI-Ions) even my profiles, so take it from someone who has done it. Its not worth the extra money in that plane. Get a good NI-MH and drop the whole regulator thing. Your weights will the same and flight times will be close to the same. IMO, you should yank those digitals out of that plane and put it in something a little bigger (then add the Li-ion batteries). I am flying mine with standard servos and its the wildest plane I own.