Hi Stutho,
I think the problem is that most chain whips these days are made for holding a cassette to undo the lockring, - which is probably never going to get as tight as a screw-on sprocket. So to break away a tight sprocket needs a lot of leverage, or if the whip is too short, means hitting the handle with a lump hammer (in my case!) - which is where the more flimsy handles tend to bend because they have no rigidity in the side-to-side direction. So a track sprocket whip (Park SR2 or similar) is probably the right tool for the job, as you say, the down-side is the price, for occasional use. Which is where a robust DIY job has the advantage.
The other way to do it would be a peg spanner large enough to go around one side of the central locking tool with pegs to fit between the teeth on the sprocket. Again, a piece of (heavier) flat bar would probably do the job, with a cut-out in one side and two bolts protruding through. I have used things like this in the past for dismantling free-wheels and removing track sprockets. I have some old sash-cramps at home and the long flat bars have been seriously modified at times for jobs like this!
I am sure there is a market for a simple, robust tool bearing in mind the number of Rohloff hubs now in use.
Of course, the wheel can always be taken to the LBS to get the sprocket removed, but if you are like me you are probably doing these things at times when the bike shop is not open....
Rgds
TVC
