I have had the Sling Pack for about a month now and I'm very impressed with the functionality. I also purchased the backpack harness kit to convert this sling into a backpack which suited my purposes more as I tend to pack heavier.
I like that there are hidden rear pockets for anti theft purposes and that you can expand the bag significantly with the outer pocket. The compression straps keep the bag tight and the materials feel very premium.
I would recommend giving this bag a pick up, there's nothing out there that has this aesthetic that Code of Bell has been able to capture.