Nope, not at all. They weren't stripped into mono because of *ram* limitations, but because of *rom* limitations.
That is, *if* the s910 *had* any expansion memory (which it doesn't).
But the s950, with its mono drums, brasses and strings? It would absolutely be possible to record your own stereo versions of those on.
But why would you? It would be the same stereo samples of drums already on T4,T5,sx700,s970, and newer. So you'd have to make an expansion pack for s950 *only*. And that is limited to only 64mb of expansion space... meaning you'd have to pick and choose what to fit into a very limited space.
Anyway, it *is* possible, but the amount of work required isn't trivial. But I know some on here have created their own expansion packs for s950 (pjd comes to mind!).