How well do they ride?
They ride far better than the 11 way adjustable Aldans, Bilsteins, 1st and 2nd generation Legends that I've owned.
How do they preform when riding the twisties?
They work very well. With the urethane bushing change they stiffen right up and eliminate the tendency to want to twist on the bushings (stock bushings are soft).
And can you adjust the stiftness at any height?
No. You add air to stiffen which also adds height. They are different than the motorcycle specific shocks. At any ride height they perform well.
In case I'm riding one up and the bike low but want it stif so I can ride more aggresively?
No. For me when riding aggressive I have them aired up so I don't drag bags. Since I've only ridden with stock bags for less than a year total since 01 my experience with this scenario is limited. Once aired up you can increase the stiffness. I have ridden hard with the shocks fully dumped but not in the corners.