I always sort my brass. Usually, my reloads are done with only Starline or Winchester brass, but occasionally I get stuff in from a friend that's something else. I always sort my stuff before tumbling, while I'm in the cleaning mood just from the range. Never had any problem, just tumble one type at a time. I tried using those bags from Lyman, but found them to be more trouble than they're worth. That and they don't allow free flow of the medium around the cases.
Sorting of cases is very important as different makes have different internal volumes. This may not be a big issue with something like a 357, but for 9mm it can be critical.
I reload about 1000 9mm and 40S&W every week to support my habit, and those of my friends on a Lee Pro 1000. Never had any problems, after about 25000 rounds. Just the usual maintenance and cleaning.
Due to the set-up of the ranges here, I usually loose my brass over the firing line (unrecoverable) and get new stuff long before it becomes unserviceable! I've loaded tons of "Range recovered" brass with no problems, although usually to low power levels, and all 40 brass from Glocks goes back in the trash can. Why flirt with disaster?
Remember, no matter where you go, there you are!