I ride a Rohloff and you do not shift them under load. Most of the shifts will tolerate a light load, but going from 7-8 while steaming up a hill will immediately bind the gears and you need to backpedal a few teeth to get it unstuck. By the time that's all sorted, you've lost your momentum and need to downshift again, not to mention taken months off of the lifetime of your very expensive hardware. As you can probably tell from my description, this is a mistake I've made. Binding up your brand new $1500 transmission is a great lesson to never do that again.

The Rohloff can not be shifted under load. You can shift by quickly letting off power, shift and then resume like you can do with other planetary gear systems.

Here's a discussion on the subject of shifting under load, with opinions from "both" sides:

http://thorncyclesforum.co.uk/index.php?topic=4172.0