Skelly,
Like the others have advised GO with a White's coil. In Stock form I think the machine comes with the 12" Spider Coil and it is supposed to be a good coil. I'm not certain of what construction the Spider coil is, that is elliptical or some special layup of the internal wiring, but the DD 6 x 10 is a double D configuration coil and I believe it's construction purpose is for good separation of multiple targets in trash areas but check that out to be sure. Ask White's, give them a call.
Also, whites is having a coupon sale right now so check out what they have going for the MXT Pro. AND, be sure to obtain price quotes for the setup you want from mail order houses and take those quotes with you to your dealer to see if the dealer will match or beat the online quotes. When you purchase local you can return to the dealer for help. And, finally see if there is a detecting club in your area and attend a few meetings and ask around as to what the locals use and why.
Good Luck with your purchase, have fun, read the manual, re-read the manual, practice, practice, practice, plant a test garden (coins, foil, nails, etc.) and use it to see how your machine reacts to the targets, be sure to plant each article far enough away from the other targets like 2' away.
Final note: Good earphones are worth the expense and so is a good electronic target probe as well as a good digger like a Lesch.
Regards, 63bkpkr