RE:Fanny Pack Alternative
Interesting! I am currently a chest pack fan, preferably w/ removable rear compartment. That gives the long day/short day option without transfering any gear out of the front. It is very steady in it's position due to the harness design. The one glitch is that it's not as simple as it could be to retrieve items out of the back. This design offers an interesting way to deal with that.
If the sling design is less stationary than the traditional chest pack harness and tended to get in the way, I would sacrifice the convenience of fetching the from the back in favor of the unflappable chest pack harness. On the other hand, if it stays in place and doesn't bother me when I climb a fence, paddle, cast, whatever - it would be a welcome new addition to the FF arsenal.
You got my curiosity, I'd love to check it out when I get a chance.