I forgot to mention the other big advantage of belts which is that they greatly reduce resonance problems.

The site you linked to has mentioned what I did:

'Even though the output speed is reduced by the reduction ratio, some systems will actually have their overall speed performance increased due to better use of the motor's torque curve.'

I wouldn't hesitate to use belts again - I will when I convert my lathe, though admittedly that's partly because it'll have a rotating ballnut.