Most high end fly lines have an end loop incorporated into them. Those that don't most guys will nail knot a heavy piece of mono with a loop on the end to achieve the same thing.
Many fly leaders already have a loop in the end for a loop-loop connection. Those that don't, well it takes seconds to tie one.
The loop-loop connection is favoured by flyfishermen because it allows for quick change.
Bear in mind because fly rods are much longer this connection is almost never reeled into the guides.
It would be an incredibly easy thing to incorporate a permanent loop at the end of your braid.
Tying a loop in your fluoro leader as mentioned is easy and takes seconds.
Having been familiar with this type of connection for years I would never consider it for anything besides flyfishing.
It's simply not streamlined or small enough. It wouldn't be finesse enough for my liking and wouldn't reel through the guides easily.
If I'm concerned about the ability to change leaders on my braid I'll use a microscopically small black ant barrel swivel. The same ones I use for steelheading.
Been doing that for years. It works great and is very subtle and stealthy. The only drawback being I don't like to reel the swivel, small as it may be, through my guides.
The link to the fluoro swivels which I posted earlier should be looked at again.
They allow for quick change plus won't be as hard on the guides if you're running a long lead.
I honestly don't see how you can improve on this:
http://www.aquateko.com/