Hey Brian, what's that all about? LOL

I'd go with the 10XL. Actually, I'm a big fan of the 9XL, but the 10 will do fine. It will also leave lots of room for going to 5S later.

As for blowing up equipment, it doesn't matter how much you pay for a piece of equipment. All of the smoke smells the same when it decides to escape.

The MM is a great investment. For the price, you could buy a spare. Later, when the Lehner motors become more readily available, all you'll have to do to upgrade is get the Lehner.