One advantage is you are minimizing abrasion to the string serving by shooting off a loop. You are also able to get rid of any brass nock sets you had on the string. Additionally, I find having my release directly behind the arrow, rather thanbelow it, allows me to shoot more consistently. A loop also allows you some additional fine tuning relative to draw length. As for releases, other than a few like the Winn C-10 that are made specifically to shoot off the string, almost any release will work with a loop (single and double caliper and hook releases).