The 600 has more power and weighs less
both in considerable amounts. Two of the most important things to me too
You'll have to look for a tagged/ plated 600. They are out there, but didn't come stock.
The kicking really isn't an issue to me. 3 max when it's cold and 1 when it's hot. That's worth 50lbs to me.
Maybe some more suspension and whatnot too, but weight, power, and tag are the three biggest I'd say. And all are big.