I have seen one at the hydro store too, but I adapted my own. It's not the weight I am worried about except as it relate to possibly overloading the motor on the lineal mover.

I am just about to go take it down and adapt it too a three way modular unit which will raise the MH in the middle of the 2 HPS (for heat reasons and distance from plant tips) but run them on the existing motor and trolley. I will post my results.