Thread's a bit old, but there's not a lot of discussion on gimbals on this site and I recently got one.
Before, I was trying a 600mm focal length on a little compact travel Manfrotto with small ballhead. This tripod is great for travel, but my keeper rate while using it not in self-timer mode with the T90 was about 50% at 1/125. So a 2 stop improvement over handholding. When using in self-timer mode, there's some pretty visible shaking of the camera from the mirror vibration. It also makes focusing harder if the viewfinder image is jerky.
Now, I'm trying the same setup on a much sturdier Tiltall aluminum tripod with 3-way head, and a Neewer gimbal on top. It took some adjusting and tightening, but I can already see looking through the viewfinder what is probably an extra 3 stops improvement in handholding vs the flimsy tripod and ballhead. I leave the 3-way head completely tightened and pan and tilt with the gimbal, it's extremely smooth in the movement and I don't see any of the jerkiness in the viewfinder that I was getting with my previous setup. Can't wait to go take it out into the field. The extra height from the gimbal means I can only use 2 of the 3 leg extensions of the Tiltall and it suits me as a 6 foot person. The Tiltall's central column at full height still stays pretty well locked in as far as vibration goes and with less leg spread it's usable in tighter areas.