I did not get to ride the RC 390. I am not tall enough for the demo ride (I didn't feel comfortable).. I did ride the 390 Duke.
I was impressed If I were to upgrade the KLX that would be it. Great power, loved the display, and the suspension was great.
There was a gap in front of me (on purpose) and behind me. I got her up to ... Faster than speed limit by a lot.... Ran through the gears.... Basicly I rode it like I stole it.
It handled very well.