If you're going for your MBA, you want the least stressful job, and it sounds like you have it now. Besides which, if these people are good to you and the hours aren't, as you put it, "suicide hours," then you're in a good spot. You might be in even a better spot. Sure, you could be getting better money, but is it worth the higher stress, and the possibility that you won't advance
from a stressful situation? Nah!
Will the people you work for let you come out to Willow Springs for Wednesday OTRs? If yes, then you should definitely keep the job you have now.