I just recently sold my Steyr AUG and got a SCAR. But, when I had it, I used an Urban ERT sling... But, not his standard AUG setup. I came up with my own mounting points.
I had an Urban ERT sling years ago, back when I had an MSAR STG AUG. Back then, many people discovered that using the front sling mount would get the sling caught up in the charging handle pretty easily. So, some of us would attach the forward mounting point to the side rail - and run the sling up under the gun - in between the trigger guard and the forward grip.
Now, the Steyr AUG doesn't have as long of a side rail as the MSAR AUG did. So, if I were to use that side rail, I would have to mount the sling further back. Also, with the Gearhead aftermarket charging handle I had installed on the Steyr AUG, I tended to lay the gun down on a flat surface on the side WITH the rail (right side). I didn't really wanna put the front attachment point for the sling there.
So, I ended up using a quick detach GG&G mount - with the rail portion on the optic rail. I rarely kept the sling on the gun. But when I did, this setup worked great. It may seem complicated, but when the gun is hanging on you by the sling, it works very well.
I had Urban ERT make me an 8" piece to attach to the sling. That gave me more than enough length to run it down and around the gun. I probably could have gone with 6", but I had ordered a 5" piece years ago on the MSAR, and it just barely worked. This time, I decided to give it a little more length.
See below: