I haven't contributed to this thread directly, though it looks like my Amazon review came in handy at one point...I'm glad if anyone found that helpful. I just recently came back from a trip to Europe (4 countries in 10 days) using both the Rothco bag (branded "Everest") and Gravity Trading bag and wanted to post up some insights.
Gravity Trading: I still maintain this is the higher quality bag of the two, but I wish I'd gotten it in green instead of black. The black just shows dust and dirt way too easily. This, along with the Tenba insert, was what I utilized 100% of the time we were in transit between cities..trains, planes, etc. when access to the camera wasn't priority #1. The ability to zip every compartment and know it wouldn't be spilling contents whether it was stuffed under a seat or carried on a lap or set on top of a suitcase was invaluable. It's rugged, secure, and I find the wide strap completely comfortable despite carrying all of my camera gear. Some would find my particular setup modest, but to me a DSLR and 3 lenses, along with batteries, cables, filters, etc. adds up quickly. Surprisingly - I found that I did NOT prefer this bag when moving through the cities day by day. The zippered main compartment remained completely open for the one day I did choose to use this bag, and I still found myself irritated at the zipper flaps as I removed and stowed the camera. I also realized that my 17-55mm zoom was what I needed 98% of the time, meaning the padded insert and extra gear was all wasted space and weight. In addition, and this is a VERY small pet peeve - the flap is about an inch and a half too long! Even fully packed with the insert and all gear, the main flap folds over further than the velcro it is meant to meet. I have no idea how I never noticed this before, but when it bothered me to no end.
Rothco/Everest: After day 1, this became my main day pack, WITHOUT the Tenba insert. One day with the full kit, and after that I limited it to the T2i/17-55 with the hood reversed, extra battery/memory card/filters and that's it. Everything else went in the main compartment along with my jacket and whatever else I found I wanted to store there, since I now had actual space without all the padding. Access was quick and easy as I usually kept the camera sitting on top of a light jacket and there was no fussing about with zippers or padding. I found the open main compartment and pockets to be no hindrance in securing my belongings, though I have modified mine by adding additional velcro to the main flap for a more secure closure. I carried this all day and night, on subways, streets, trains, etc. and never once felt as though my items were in jeopardy, although as a caveat, I am not careless with my belongings and maintained steady awareness of who was around me and their proximity.
The long and the short of it: I'm glad I own both bags, but if I could pick only one, experience has shown me that I'd rather travel and shoot out of the Rothco for its easy of use. If I could have my way, I'd simply upgrade the Rothco with better/more velcro on the flap, and add the document pocket to the back that the GT bag has. That would've been perfect for the maps I was constantly using in each city, and the Rothco just doesn't possess a quick/easy document solution.
All of this is said with the understanding that I am an amateur photographer who was on vacation first, and a photographer second...my needs and expectations for this bag are likely quite a bit different than others who are using it solely as a "working" photo bag. I thought the perspective might be helpful for those of you who ended up with the "wrong" bag, however.
-Jon