I don't wanna get anyone in trouble. The people at Minelab are terrific people, in fact, you could even call them with your question. I have an SE, I called Minelab and asked about the MP for my second machine. There was one on Ebay I was interested in. I was told I would not be happy with it. they strongly suggested the 70 over the MP, and suggested a few other machines also. I assume that part of there idea was that I already had an SE. They said I just wouldn't be happy with the MP. But if you do the math it still comes out the same in your case. It was said that the MP is slow in response. Sense I've had other discussion with Minelab I trust the advise I was offered and stayed away from the MP. What I did wasn't one of the options they suggested, but I'd guess they wouldn't have disagreed. I bought an EX 2 for my second machine. I really like what I have now, I'll use one for my smaller coils, trash area parks etc. and just general backup. who knows what else I'll come up with. The Explorer is a great machine! I like the little subtle differences, and everything is interchangeable. This last parts about me, but you get the point. You can probably pick up an Ex2 for about the same price as an MP and get a lot more machine!
Good luck. PP