Anyone 670 naysayers here actually know what they are talking about? My 670 runs with 800's all day, and yes, rider skill is important but the 670 was a strong sled and if you know how to tune it, it is a potent machine. That being said, I'd go with the 700 RMK. Newer chassis, more aftermarket parts for the 700 and more replacement parts still available. The 670 is a very capable sled, but if the prices are comparable, get the 700. The stock power on the two was about comparable, but the fact that the 700 is 3-4 yrs newer is too a big advantage.