Respectfully disagree as the SL 112 is only a 250 watt cab. If paired with an SL212 it may become overwhelmed.
Overwhelmed? No.
The amp "sees" 3 of the same driver, each getting an equal amount of power.
Completely depends on which cabs you're talking about.And 1x12 generally speaking isn't as capable as a 2x10.
I'll take my SL112 over my Ampeg 210, Hartke HD210 (ended up with that one in a trade). or another "boutique" 210 I've owned.
Much fuller sounding to me.
IMO, the SL212 is pretty conservatively rated.