I'd venture to say that no line system requires more loops than the complex / interchangeable hybrid line systems for Spey casting with sink tips. Steelhead Guide Ed Ward showed Andre and I some very interesting loop designs I will be considering toward my own loopiness. The most important factor was the lack of rigid profile in the attachment of the loop to the line. Even 3/8" of hard material (sleeve, cement, etc) can catch in the guides when there is pressure from a fish on one end and an angler bending the rod on the other. Although I feel my current loop system is pretty good, there's always room for improvement.
Another key to Ed's loop system is the impregnation of aquaseal in the braided nylon to provide hingless yet supple body to the braid. I've used Aquaseal to seal the nail knot which holds the loop, but not in the same manner as Ed and there may be a lot of benefit there. It might even make loops in the middle of a head (ie: hybrid configurations) bearable for striper fishing where there is constant stripping of line thru the guides during the retrieve. This drove me away from hybrid heads during earlier experimentation.
In any case, if the loop is used for leader attachment, you might consider the alternatives of (a) epoxy splice of butt loop (b) nail knotted butt loop. These are smaller profile alternatives to the braid. If used to join two line sections together (re: shooting heads) some form of loop system is unavoidable.
Bob P - What's the trick for securing the end of the braid when pulling it inside itself with the threader? The tool Bob D mentions has a 'flapper' guard thing on a tiny hook on the end of a needle-like device that let's it hook onto the material and hold it while it is pulled inside itself.