I think the system are pretty solid but with a lot of space for improvements. I would prefer to have better balanced and nerfed systems instead of "wild" new systems with an even bigger chance of failure or imbalances...
But imo they should hire a few additional authors for an expansion. Why not letting some guys or gals contribute to the game like it happens for Torment, e.g. just for writing a companion or a questline? The underwhelming amount of writing is one of my biggest issues with D:OS, not necessarily the quality but the amount of lines and dialogue options, especially compared to the old CRPGs.
