Here's a quick example of my motorized slider's ability to go vertical.
The slider is pulling a Canon 60D with both a Zacuto Gorilla plate and Manfrotto quick release plate, the heavy Tokina 11-16mm, and I even threw on an LED light just for bragging rights. ;)
Servo handles it all with ease, super smooth and doesn't stutter once, which means there's plenty of room to go heavier if needed (battery grip, etc.).
Secondary shot was done on an iPhone 4, and yeah, it's that hard to keep steady...
Track is 'Do the Astral Plane' by Flying Lotus, from the album Cosmogramma. (itunes.apple.com/album/cosmogramma/id367788829)