I've always wanted an easy way to play rubato with these workstations, especially for accompanying vocalists. The free styles have been my solution so far.
This is what I found to control/vary the Master Tempo with an FC-7:
Activate the 'direct access' and move the FC-7 to get to the setting screen. Touch 'Foot pedal 2' (that's where mine is plugged into): in Category go to Overall (pg. 2 of 2); in Function, go to Master Tempo (pg. 2 of 3).
I'm sure there are other ways to do this but for now this will do for me. It's a function I have wanted for a long time and didn't even know it was available on the SX900.
This may be old news for many of you but for me this is a great find. -Ed L.