The mapping I used for years before getting my first Midi Fighter Twister.

S4: key controls with shift and filter/cue points. FX selections on the mode buttons. Mixer FX switch through mid eq, pan through low (using shift). Gain knobs on beat adjust fine tune (for bpm traveling songs)/shift for gain adjust. Gain button sets record for the deck it hovers over (shift + Button to reset gain)

f1: mostly normal sample capture/pad with of freeze mode control for deck A & B (hold button for easy release and return) replacing sync and quantize

Keyboard: function keys set for solid number bpm (for easier sync to keyboard and mpc). EQ on/off and reset through the keypad.