Upload & Sell: Off
I use the ThinkTank Retrospective Lens Changer 3 (black) for weddings at around 8 hours give or take. I've not used many shoulder bags to make a solid comparison, but I don't think I will be bothering now that I have this bag. The strap is thick and wide and does not slip on my should. It has 3 lens pockets long enough for my 70-200IS II. During events I'll keep my lenses mount-side down, hoods attached and upright. My 70-200 hood pokes past the lip of the sleeve just enough to pinch a petal of the hood and slide the lense out for a switch. The bag has a flap loose enough that it can still fold over entirely. Of course it does not carry a body as it's just the lens changer bag, but there are other options in the Restrospective line that do.
With a camera around the neck and the 16-35 attached, you have room for the other two lenses plus a bottle of water (room temp to prevent sweating), or even a fourth lens if you are comfortable doing a one-handed lens change. There is a SMALL pocket up front that could hold some AA's or memory cards and a sleeve on the back wide enough for a note pade, magazine, forms, pens, business cards, etc. etc. The cover has a velcro seal that can be covered to allow quick access to the lenses, or just leave the cover backwards against the hip to have immediate access to lenses.
No. I do not work for TT. lol. I just love this bag.