The easier method would definitely be pre-preg with an internal pressure bladder. This then requires drilling holes in the piece afterwards to remove the internal bladder. 

I don't have a clue about joggles and i can only assume you need experience to do it. 

It's also less consistent and more labour intensive. When you're trying to sell things, you want to be able to pull them out of the mould, trim them up as quick as possible and then do any bonding quickly and easily and know everything is aligned as it should be. With a butt-joint, your trimming becomes quite difficult because if you go too far then you have a big gap but if you don't go far enough then they don't sit together properly. So it's a lot of trial and error that can add up to hours and hours and hours in a production run. Applying the adhesive becomes a task, because you need to keep it off the cosmetic surfaces.

Essentially all you are doing is making an inch of the wing twice, and using the sheet wax to make one slightly recessed so the other one slots over the top of it, both locating the halves together and providing a good amount of surface area for bonding.