The biggest differences between ABA and non-ABA schools are the numbers and limitations on where you can practice.
LSAT scores, Bar pass rates, tuition costs. All are typically higher at ABA schools.
If you attend a non-ABA school as I do, you have to have a realistic view of what you want to do after law school. You will not be interviewing with the big firms. That does not mean you will not have a rewarding career and possibly make good money.And you will probably need to plan to stay in state for your practice. Although, many states will let you sit for their bar after 5-7 years of practice in good standing in your home state. Before deciding on an ABA school you have to be on board with it 100%.
Never bank on a school that says they are working on ABA status. There are no sure bets. Some schools have been trying for 10 years and have not made it.
Transfers are really not an option. In the rare case you may pull it off but if you are that rare of a case you probably should only apply to ABA schools if that is important to you.