Justin,
I did just about exactly what you are proposing, except I came from ERAU. After my private I was disgusted with the scheduling and decided to go the the FBO across the field. Things progressed *much* quicker. I really wouldn't worry about 61 vs 141, I don't think it matters at all. You learn the same stuff and meet the same standards. I learned some important things at ERAU that I am sure you are familiar with. Example: flows. It is amazing how many FBO's fail to teach this. Don't stop doing them! You are going to have to watch your back with a few things like this, but hopefully your instructor will be on the ball. You have learned some important things from the UND way of doing things. You have also learned some things you don't like. You are going to be all the better because of this. Take the good and leave the bad.
AZ is great for flight training. You can fly in the summer, no worries about that. You can find IMC if you go look for it. That is much better then having to sit it out because you are trying to practice your ground ref and it is down to mins.
You are also choosing to go to an inexpensive school. Smart man! It will benefit you way more in the long run then making $600+ loan payments every month for the indefinite future.
Other then the private ground school at ERAU, and pre/post flight chats, I never spent a minute doing ground with an instructor. I preferred to do it on my own time. This works for some, others have a different style of learning. It is entirely possible though. If your new instructor thinks that you need ground instruction then make sure you know what he want to talk about next time, learn it all ahead of time, then when he starts teaching say "how about I explain it to you this time, practice for my CFI ya know?" Begin flaunting your knowledge at this point and they will begin to understand your style.
I wouldn't worry much about where to get the CFI and being *committed* to a school. CFI's are in great demand and if you are willing to move then you will have no trouble finding work. Maybe try to work out your school/degree so that you can finish it online. That will give you quite some freedom.
If you fly even one hour a day (and if you have the money I predict you will fly more) you will be done with all your ratings through MEI in less then a year. The more you pack your flying together, the better you learn (I am sure there is some limit to this, but 1-2 flights a day seems favorable).
You are making a smart decision. Good luck.