I'll be interested (and surprised) if an S1000 shock fits an R NineT, or is an improvement at all. The rear suspension is obviously a completely different setup and will have different leverage as well as the sprung and unsprung weights being different, so even if the shock can be hacked about to physically fit the spring rate and damping will most likely be completely wrong - and the shock length and stroke will likely be different too, which will mess with the suspension travel and overall geometry.
For the amount of work it will take I struggle to see why anyone would bother instead of getting a Nitron/Maxton/Wilbers/Whatever shock which is sized, sprung and valved for the bike and will fit without modification tbh. But maybe that's just me!