gimbal head for 400 5.6

[biscuitthief]

I'm currently looking for a gimbal head for my gripped 7d and 400 5.6, and like the look of the Jobu range. Their site recommends the Jr3 but warns you of limited upward movement due to the balance of some lenses.
Anybody using this setup? Is it really limited? Any other brand suggestions would be great aswell.
Thanks
Chris