Jaap, if you see this, never ever you will be able to calculate the number of possible states for this one
Including jumbling, you mean, right? I think it could be calculated, it won't be easy, but it could be done. Of course we have to define what a state is carefully. Do we want to count (for instance) solved state and solved state with UF+72 as the same, or are they different because different moves can be done in each position? How much of the puzzle can actually be jumbled? Does it still count as a state if many axes can't be turned? And so on. There is a clear limit to how much jumbling can take place (each axis holds two groups of pieces, and each turnable group MUST hold two centers and a corner).
Here is an interesting jumble: (UB- RD- FL-) (FD- RB- UL-). It leaves three 'twisted' center pairs and only three turnable axes.
Interestingly there are over 24000 times as many cube-shape states possible if you allow jumbling than possible if you don't. Because a jumbling move can typically only move 2 centers out of place at once (of 24), it would require a huge number of moves to evenly, randomly scramble among these states!
Care to make a slow motion video of a jumbling sequence (from solved) non-solvable with normal non-jumbling turns!! Please!!!.
Try this: UL- FR- UF180 UL+ FR+ UF180.