I'm not sure... shall you? If yes, it's probably because you prefer the form and having the 'classic' toolbelt and trackpad. If no, then it's because you don't need those features and the Q10 still does what you need it to.
As far as I'm aware, the Classic has the same specs as the Q10, other than the display size.
If you're going for the Classic, you're only buying the toolbelt and the bigger screen. The choice is yours.
I was thinking about the same thing, but then after doing my homework I realized that Classic has pretty much the same specs as the Q10 except for the toolbet. Its a little bit faster for android apps but everything else is pretty much the same. Unless you really want a Classic or a change.