I feel for you, I have the same, slight, regret regarding the Enduro. The Catalyst is very capable and exciting off road but the mud clearance and stropping power of discs is tempting. The Catalyst's versatility go some way to making up for these regrets. I've fitted Magura H33 hydraulic rim brakes (£100 from Chain Reaction Cycles) and am very impressed with the improved performance. I'm aware of the rim wear issues but figure that you have to account for it with any rim brakes so what's the big deal. I've enquired on the Rohloff owners forum as to the cost of converting to a disc brake speed hub and a it's reckoned to cost in the region of £200 plus £100 for the ex-box, then you'll need cables. Getting the frame modded with a buzz brace between the seat and chain stays on the left, the V bosses removed and the frame resprayed make it almost worth starting again. Shame the Enduro is being discontinued... Curtis are the only other frame builders doing the same type of bike but they use sliding dropouts rather than the far more convenient EBB.
As for small matter of the Son hub dyno off road, not a clue mate. Sorry.
Cheers, James