The soil in your area is very neutral. (very little mineralization).
I don't know much about either detector, but a lot of guys around here really like the Minelab. I use an older Fisher CZ6. It will go deep, and I can use the sensitivity maxed almost every where, but it's very hot on nails.
Thats just my two cents worth. I also wouldn't rule out a Whites XLT or MXT. There are a couple of multi-line detector dealers in the Minneapolis area. You might want to check with them.