One thing to consider is resale and long term value. I believe, and have spoken to others inside the industry who agree, that the MP215 cars will have a higher resale and long term value compared to one either without the MP215 kit or ones modified with other parts. There are multiple reasons, one is the MP215 cars are more exclusive which drives demand. The MP215 cars would tend to be more reliable and the retention of the full warranty means repairs were being done and not kicked down the road. The MP215 kit is also accepted by Ford, which also brings value. With all of that said, I don't have the MP215 on my car. The warranty issue was a bit of a gamble, but I think it was ok for me. I am soon to be out of warranty, have a modified car, and never had a single warranty claim on the car. The modifications never affected the warranty on my car, so the upcharge for the MP215 kit to protect the warranty wasn't worth the expense. My theory was that by sticking to proven modifications, a tuner that understood my desire for reliability over power, and taking good care of the car would keep the car out of the shop. Warranty is meant to protect the car against manufacturing defects, so I gambled that my car would not have many of those issues and the modifications wouldn't push the limits of the design to where there would be an issue of "is this covered or not".
In short, if you want something more exclusive, no concerns over warranty coverage, and potentially has a higher resale value, then the MP215 is a good direction. If you plan to do more with the car than the MP215 kit offers, not terribly worried about warranty coverage (remember, the warranty is only affected if the aftermarket caused the failure), and are operating with a tighter budget or planning on modifying the car in stages over time, then the MP215 isn't for you.