Elmo, you didn't state your goal other than working for a national somewhere down the road. From that, I assume that your goal is to fly people. Here's me two cents. The pax industry is bad news right now. Yesterdays conventional wisdom is out the window. We all know that the big money and easy schedules come with the majors, or rather they used to. A year ago this time, I'd tell you to go to work flying people. Now, I say find a job that you can be happy working for five to ten years. I consider myself extremely blessed to be working for a company that pays reasonable, and have a contract that dictates a decent work environment. Because, I don't think that any of those big money jobs from yesteryear will be coming my way anytime soon. Nor will one be going the way of more than a couple of hundred guys a year who happen to get on with JB, SWA, FedEX.
Bottom line, the upward mobility in the pax industry is on hold. I say don't go to work for a company with poor pay and work rules(Pinnacle), because you will probably be there for more years than you expect.
I'll defer to SDD about MAC, but as to box haulers in general; Spirit has a bunch of you. Along with the normal mix of retired Generals, Colonels, Corporate jet drivers, five year military vietnam era guys, commuter dogs, and guys who had bad luck at Midway (original), Braniff, EAL, PanAm, AirFlorida, PrivateJet, etc. Freight Dogs make good people pilots, and I don't really think that it is a stigma worth worrying about.
Good Luck,
8N