570/390 My feelings about the 390.
I am a bigger guy. 280lbs. I have both a 570 and a 390. I've always ridden larger bikes. The 390 is my first smaller bike. I bought it for my son. But he is not riding it so I am.
I ride mainly between 12000 and 5500 feet in elevation.
My rides include mountain trails all the way down to gravel badlands and sand arroyos.
I've always liked more power. I like to be able to blip the throttle and lift the bike or to bounce over the tops of woops.
My 570 runs hot on trails. I added the 70-degree tank and that has helped some. On those same trails the 390 doesn't run hot at all.
I ride the 390 about the same speed as the 590 on the trails. Speed has more to do with my skills than anything else.
I know that the two bike weigh almost the same. But the 390 is a lot more flick able. It's amazing the difference in the feel between the two bikes. I'm thinking that it has more to do with rotating mass than anything else.
One can adjust the throttle and riding gear to get the same speeds and power out of the 390 as the 570. What I mean by this, is that both bikes pull hard. Both climb about the same. They both run high speeds well. The 390 doesn't mind running 70 mph on connecting roads.
Coming out of corners on the trails is where the 390 really shines. It dosn't rip your arms off. The power is very linear. This is also the biggest problem. If you blip the throttle the 390 is smooth. The 570 has a hit. I use to use that hit for jumping.
When I am on the 390, I don't try to ride the tops of woops.
If you ask me, I'd say that two wheels is all you need.