Defense standards in a game with overs

[bobbyi]

Live 20/40 game with overs to 30/60. Cutoff open-raises and it folds to you in the big blind. You both have overs buttons. How different are your defense standards here than they would be in a game without overs assuming that the cutoff raises with exactly the same range of hands? What if you know that the cutoff is an expert player and thus will adjust his standards appropriately to the fact that postflop will be in overs if the BB defends (for the sake of argument, let's suppose the button and small blind don't have overs buttons)?

(For those who aren't familiar with overs buttons, the effect here is that preflop is a $20 betting round, but postflop will be played as a 30/60 game).