It would be more of a reliability/stability issue, rather than a performance one. Right now, the spin only hurts the rocket, as we're stable without it and we don't need it, so it's a waste of energy. In the future, we'll be flying outside the atmosphere, so fins won't work. I assume we would need a secondary form of stability to keep the rocket pointy end up for this phase of flight, and spin seemed like the easiest solution.
As far as the balance dynamics analysis, there was none, and likely won't be in the foreseeable future. That kind of analysis is above my team's pay grade at the moment.
