The closer to the cg you go aft, the more efficient the process is to produce altitude. Downside: the closer to the cg the hook is, the easier to break wings by minor attitude changes like that extra click of up trim or finger twitch of up. Using a winch, when you see the wings assume that bowed diehederal look, you slow down the winch or even stop for a second or so, toss in some down elevator trim. A bungee is all or nothing, you cant slow it, the
BEST you can hope for is a full down elevator release of the hook as the plane speeds up
. Many times it would get tangled up and require the landing with it attached which is a huge pain somewhere unpleasant.
See the comments made by
@Hai-Lee to mayan about bungee launching test flights. I personally prefer to start about 2" forward of the TESTED cg and move back in 1/4" steps to no closer than 1/2 inch
This is also why most people carrying gliders use a nose hook for aero tow, and a cg hook for winch.