M7 Vs M8?

[ACP]

A stock M7 is lighter than a stock M8 I would stick to an M7 prior to the 2010 M8 due to the fact the hp is very similar but all are good, Oh and my son is selling his M7 with a lot of extras for 4500 exc shape low mileage. lol

So I posted another question in a different category, questioning what used snowmobile should be my first. I was steered to the Arctic Cat M6, M7, and M8, preferably 2007+.

I am too big for the M6 (220lbs, 6'2) so I am here asking what you would buy in my shoes?

My price range is max $7000, so I of course want to get the best bang for my buck. I plan on doing field, ditch, and some mountain riding in deep powder.

What would you buy, or avoid?