Something to keep in mind, is that quality 2-point tactical slings almost all come with a feature that allows for 1 handed adjustment, making them extremely flexible in how you use them. Add one or two QD attachment points to change up where/how the sling has the gun hanging, and you can carry your AR just about any way you could possibly want, whether cross-body or over the shoulder, etc.
One I've been working with for a while also has the ability to be used as a shooting sling, where you slip your arm through and wrap it, to steady up the rifle. So far it's been a useful tool for some of the more awkward field-expedient positions:
The RS-3 is fundamentally different from the RS-1 and RS-2 in that it allows the user to ‘wear’ the rifle around the body, which enables it to be available for instantaneous shooting from a carry position. The advent of this mode of carry is relatively new, having become popular in the late...
rifle-craft.com