I am one who never zips my bags and prefers the "open concept" so I can't help much, but I will tell you that the other day I was on I-75 and had to slam on my brakes, Bandit went flying, but nothing spilled out. That magnetic closure works!
As far as the pouch, I use it for items I don't access frequently, but want to have with me (card case w/store cards, lotion, mints etc.) and put my wallet and phone in the main area. I am not a shoulder bag fan, but love Bandit!
Of course I use it mostly on workdays - to the car - to the office - back to the car, so not much need for in/out access. I did take it shopping last night at Dillards and didn't get frustrated with it (I could have always just carried the pouch in via the top handle as another option if I did get frustrated). If this is your daily running errands bag then it might not be best. Of course, for errands I never take a big bag, just a small crossbody.
Good luck, that puddle of leather is hard to resist!