Definitely this.
And speaking of which, know what I would really have loved in SMG2, and possibly the next 3D Mario?
Normal mushrooms (no, not those 6-health ones). By all accounts much of SMG2 is pretty darned easy / as easy as the first, save for a few boss battles and comets and what not... and I think to a large extent, this is because of how "game-breaking" (for lack of a better word) the spin-attacking/spin-jump is. Any time you fall, as in SMG1, you can spin your way out of it. Why not, instead of scattering a whole bunch of 1ups around all the time (rendering the lives system close to pointless), scatter 'Spin Mushrooms' or something around, that which give Mario his spin attack. Make us earn it.