my biggest thing is knives not fitting the pockets well. if you have to struggle to pull out/ replace a knife, you could cut yourself. too loose and they fall out and your toe could get chopped off. you could also have something to secure the knife at the blade, like velcro. really think out the location of knives and make sure longer knives will fit. (at least 12" for me) small knives/ gadgets should get smaller pockets as well. don't forget the cleaver! don't forget to account for bulky sheath's like saya's and victorinox's blade guards.
utensils, measuring cups, etc. also need a place, so a large external pouch would be best. (i carry a quart measure and it doesn't fit any knife case/ bag/ roll) it would be nice to be able to unzip it quickly and throw whatever you don't need in there. you know how limited space is in a kitchen and to take over the whole counter is not ideal during service. you could just carry whatever it is to your bag, unzip the front pouch, toss it in, zip, and go.
make sure the handles, material, and zippers are up to the task of a full loaded bulging bag... and make sure the shoulder strap is comfortable and well padded for lugging around a fully loaded bag. lockable zippers for security.
i love the styling and fit and finish of Global bags. i like the fact that the stiching is actually straight like a professional did it, not like some 10 year old in a sweatshop did it.
business card holder should be on the outside and hold many cards so your info is clearly legible in case it is lost, but also for easy access if someone wanted a card.
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I am currently using the Global G667 PRO and it is far from the perfect solution, but it is the best I have right now.
http://www.cutleryandmore.com/details.asp?SKU=4535
As you can see there is a pouch on the front, but it could be bigger. Again i wish it held a quart measure. I am using a Craftsman tool bag for that and my potato ricer. Would be nice if i didn't have to.
The pockets for the knives actually hold the blade, but I feel that limits you too much on knives and sheaths. Saya's and the Victorinox blade guard do not fit. Instead i have to use edge guards that can scratch the blade and slip off. (I cut myself because of that actually)
On the inside, there is a pocket suitable for papers and documents, maybe a folder but it needs more area on the inside to be able to zip up. similarly fitting my uniform is a bit difficult. No way my shoes would fit. if you made the bag fatter, then you can add more storage to it.
The center section is misaligned with the bag when loaded up, so zipping it up is difficult.
i had to cut out a pocket to fit my cleaver, so i am down to 9 large knives and a steel. in place of the 3 gadgets, i have 3 paring knives. i feel i have enough storage for knives, although more would not be a bad thing. my oyster and clam knife and peeler reside in a little pouch on the inside. my whisk is in the rolled up pouch. the pen holders hold pens.