Ergon grips are available from CRC who supplied me with the Rohloff specific version. I found the Rohloff (right) grip too short at 98mm so I don't recommend that route if you have large hands. I then bought the standard ones and cut the right one down by roughly 20mm with a hot blade to 108mm which fits my hand width nicely.
I find these Ergon grips with the horizontal 'platform extension' combined with Thorn comfort bars give me a very relaxed and comfy ride.
They work well for me with Thorn comfort bars, but you need the model with the longest straight ends if you want the brake, Rohloff gear shift and 108mm Ergon grip butting up to each other in a straight line. Putting separate bar ends on would probably require the brakes to move inwards to a position on, or just past, the outermost bend.
I tried Ergon grips with integrated bar ends and found they did not suit me.
In the interests of achieving large multi hand position bar ends on a 20º sweep bar, I am currently trying some Humpert Vario Hornbars - these are a 20º sweep bar with integrated large bar ends, removable for fitting a Rohloff gear shifter (it won't go round any sort of bend).
http://www.roseversand.de/output/controller.aspx?cid=156&detail=10&detail2=1254I just managed to fit the brake, Rohloff gear shift and 108mm Ergon grip onto the straight section of the bar upto the curve on the bar end. This did involve filing away a small amount of the plastic inside the forward outer end of the grip, where the curve starts on the bar end.
These are not riser bars, so I had to raise the stem to get the grips back to the same height as previously.
So far I am enjoying riding with them but have still to put in any serious mileage.
I hope this helps.