I ran my 9000's can up for a few months, but it just didn't seem ride or handle right. Flipped them around and it made a big difference. Had massive nose dive when braking with the can up on highest setting, now run setting 3 with good ride and almost no nose dive. With the can up it creates a dead spot in the shock before it starts to dampen causing a number of issues. This worked out great on my truck, just do what works best for you.
My buddy and i just installed bilstiens can up on his runner and they ride sweet!