At high speed and low angles of attack, the aircraft will roll rapidly towards the wing with the most slats extended.
About minimum clean speed, assymetric slats will have negligible roll effect.
At approach angles of attack, the aircraft will have a small tendancy to roll towards the wing with the least slats extended.
At high angles of attack, stand by for the roller coaster ride as the wing with the least slats stalls first, associated with rapid roll towards the "least slats" wing.
NOTE 1 - Most slats and least slats terms used here to differentiate between "fail" extended and "fail" not extended.
NOTE 2 - DC9 operators will be familiar with the pronounced back elevator required to compensate for lift loss when slats are extended at high speed.
Regards,
Old Smokey