Stephani-
I am an ex Jersey Mike's franchisee, and yes, that is true. As with any restaurant, consistency and quality are a top priority. In the southern states, where I am from, it's so humid, that baking requires some adjustments. Some people also say the water's different up north and you can taste that difference. As far as that goes, I have no idea, but I know of some restaurants that actually ship water down from NY to make their pizza crust(or so they claim).
Anyway, for sub shops, to me, bread is THE key ingredient. It doesn't matter if you're serving Kobe beef on them, if it's terrible bread, the sandwich is garbage. If you don't want to order your bread from a main line distributor, like Sysco(which is fine) I would HIGHLY recommend going around town and seeing if there's a good bakery that will wholesale their bread. That solves a lot of problems, namely, teaching your staff how to bake bread properly(it's an art and a science), delivery issues, having to buy a proofer and oven, racks, sheets, etc...($) and so on, plus it creates a BIG impression, that you only use a local baker for your rolls. Customers like that.
I actually would like to start a sub shop myself, knowing what I do now having owned a franchise. But my market's pretty tapped out(I sold my shop on the SC coast and have moved to Asheville, NC).
Anyway, like the bread is of utmost importance, the meats and cheeses are as well. Buy the best, and not Boar's Head, because that's what BH's marketing has led people to believe. It's not the best by a long shot, BH has just done a good marketing job. Same with Angus Beef; most people think if someone sells Angus, it's the best and think they're getting "Certified Angus Beef." CAB is a brand, and just 'Angus Beef' is not a mark of quality. Taste it all and decide what YOU think is best. Ask everyone you know-do taste and smell tests as you build your product. Same for how you serve the lettuce-prepackaged vs fresh vs. sliced, vs. torn vs. chopped(it makes a big difference). Come up with a hook; a special sauce, which could be no more than oil/vinegar, spices, whatever. Make your sandwiches stand out in quality and taste and even presentation of the sub. Learn to use a slicer and slice your product in front of the crowd and give them a show. Make a customer's ordering and dining experience just that-an experience, not just something to cram down their throat on their way to a meeting. Even if the prices end up being higher, and they most certainly will than the big chains for obvious reasons, people will pay it after they get hooked. It's a competitive business, but a fun one, and pretty easy in the scheme of things.
Email me or ask here if you want more info-I like discussing it. Good luck!
:P