Basically the answer is you can put as much as you like in the panniers. But the real question is where do you stop?
I have seen one rider with about 20 Kg in each pannier on his 1100GS. He wasn't carrying a pilion, didn't have a top box and had his tent and other light stuff where the pillion normally sits.
I think the 10 or 11Kg limits are imposed for structural and legal limitations.
I myself have had the panniers (2x41 Litre Zega's) with a total weight of around 10Kg's each, that included the panniers as I weighed them on the bathroom scales trying to balance each pannier with the other.
Trust me when I say that's a lot of weight on the rear end, especially if you add a pillion and the associated soft luggage like tent, sleeping bags and hair dryer on the rear rack.
If you don't want to break the rear aluminium spar, that sort of holds the whole rear end together, I would suggest you not overload the panniers. I've seen 4 of these crack and all were replaced by their owners in time, not something you would wish to happen in the middle of nowhere.
By the way, just what do you wish to carry, gold?
Mick.