With the new actuator, the cable housing doesn't have to move in order for the post to be actuated.My One Up post has the old cable actuator. It's cheap and easy to buy and install the new actuator. But what is the advantage?
I heard/read that the old actuator was only a problem on a few bike brands, Santa Cruz being perhaps the most notable.
There is no performance difference between old and new. I mean, unless you had one of the incompatible brand bikes.