The first thing you need to do before even considering a third party service agreement is to get a list in writing of the facilities in your area that honor that companies agreements. A half price agreement isn't worth much if you have to trailer your ride a few hundred miles until you find someone willing to deal with your particular service agreement. I'm not familiar with MBA Direct, but if they are like some others I've heard of they may tell you not to worry, you can have the service performed anywhere you like and then submit a claim yourself. I don't like that idea for several reasons. First, they may not reimburse at retail rates, so you wind up paying a lot more than just the per repair deductable. Second, when they decide to fold up the tent and move on you are the one on the hook, not the repair shop that already has your money.
I personally hate to see the MoCo and it's dealers further enriched by the sale of extended service agreements, but if someone is convinced they want a service agreement they probably should look first at the one the manufacturer endorses. Just remember, you don't have to pay the full asking price, the actual price is fully negotiable and in fact there are places that will give you a 20% discount over the phone.
Jerry