It's definitely night and day different from the Gen II Polaris RMK to a new Summit (or a new RMK, or a new Cat, even!) I felt the same way going from a 2005 800 RMK 151" to my 08 600 155"... I got stuck a LOT less than in the older sled. Now I'm lusting for a new RMK with the AXYS suspension... spendy little suckers, though!
It's awesome that your girlfriend likes to go riding. I haven't had the wif out in 3 years... she doesn't do hills and doesn't like cold, and.. and.. and... Oh well.. enjoy it while you can!!
2007 RMK 700, 2008 RMK 600, 1995 AC Prowler 2-up, 1980? AC Cheetah