I haven't seen a performance from GGG to convince me he could beat Froch , not even at MW let alone SMW. Froch UD would be the safe bet.
I see images of Foreman vs Bert Cooper when I think of this match-up.
The Lara fight would suggest Canelo loses comprehensively on the cards. Unless Canelo can lure Nunn into an ambush where he can deploy a counter...