I'm intercutting with 2/3" cams that have true 16-bit seesaw zoom servo. This is found on pretty much all high end Fujinon or Canon HD lenses. This means the op can gently press the zoom rocker and it will nicely zoom in or out based on the speed setting. One can literally creep zoom in for several minutes on a 22x HD lens or do it less than 1 sec at the fastest servo zoom. And with the optional zoom controller on these lenses, super precise zoom in/out can be achieved.

Looking for something similar w/ HPX250. So far the slowest I find is on the top of the HPX250's zoom. But that still is not slow enough nor it has an ease in/ease out. The most annoying is that when the zoom starts, it doesn't really ease in. It just abruptly starts at an already accelerated speed. Does anybody know of a zoom controller that can get close (in terms of functionality) to the servo zoom found on 2/3" EFP lenses? Or this is something that can be only be found on Fujinon or Canon ENG/EFP lenses?

Sorry, Sam, but the zoom controller on the 250 (and 160/130) are inherited from the DVX100 series cameras. One of my few pet peevs on my 100a.
It's just about impossible to get any kind of soft start (especially when zooming out from the tele end) with these, as they are only 3 step speed controllers. The need to mechanically engage the manual/servo switch means that the zoom motor is actually "clicking into gear" when you start the zoom. This is what causes the abrupt "bump' at start/stop (mostly start). As I recall, the Canon camcorders have (had) 8 or 16 step controllers and allowed a much better start/stop/creep.
It was a design choice that traded "repeatable" distance numbers for a smoothly feathered creep/start.
Even good external controllers, must contend with the limited internal speed settings.
This is the reason I almost always use the manual zoom setting. With practice, you can get a pretty smooth start/stop, although certainly not a timed creep.
Hope this helps.
Ken

Thanks for the real-world tip as it'll save me a lot of time and frustration ordering 3rd party zoom controllers and find out that the servo zoom motors in the HPX-250 just can't do it in the first place.

The manual zoom is method extremely hard to achieve. Probably I'm spoiled by the 16-bit servo zoom found on most higher end 2/3" lenses. You can somewhat away with it by pan right or left and perform manual zoom out. But if the shot is straight on, the inconsistence manual hand servo zoom is hard to conceal especially creeping. If not careful, a hard touch on the zoom ring will result in a huge "zoom breathing" where it just so sensitive to extra force. Definitely a very delicate touch and countless hours of practice are needed.