I started diving with my Cobra on a retractor. I now prefer a swivel bolt snap connected with a nylon tie, clipped off to a d-ring when not in use. Using a swivel snap does adds task loading as you have to find the d-ring and get the snap on it, rather than just releasing it with a retractor. However, with a little practice it becomes automatic.
In retrospect, the retractor was helpful as it reduced task loading while I was still struggling with buoyancy control. After I got to point where buoyancy control did not require conscious effort, I changed to swivel snaps.
IMO the swivel snap attachment method is preferable over a retractor as it is more streamlined and theres less to break. Additionally, I use my compass attached to the Cobra a lot in the quarry. The retractor always trying to pull it back was annoying when swimming very far while using the compass.
As I progressed as a diver and started to add lights, reels, a pony bottle, etc., I needed to work more and more with swivel snaps and d-rings. The time and effort used on practicing with the snap on the Cobra paid off.
Mike