Here's a nasty little bit of info for those considering mesa...
Most airlines have 1-2 year seat locks. Mesa has what is essentially a lifetime seatlock, with a couple exceptions...
FO's can upgrade into any airplane.
CA's can transfer to a higher paying airplane (if one exists).
I knew this was the case back in the day, but I was astounded (well not really) to learn it was still in the contract.
Point being, if you're looking for a specific base, be careful what airplane you go to.