To be fair, Stann also possess a great deal of power as well. Bisping fought stupid in the Hendo fight. I have no idea why he kept circling to Hendo's power.
I still have my doubts on Belfort's cardio. Bisping really needs to outgrapple him against the cage early, like you said. After that he might be able to cruise to a decision, or try putting more power behind his punches so as to finish Belfort in impressive fashion. People say Bisping has no power but I believe it is because he is so light on his feet.
I'd say Belfort hits slightly bettter than Stann, but it's his finishing ability that would be the difference. Bisping wouldnt be able to tie him up and hold it out if Belfort landed cause he has some of the best GnP finishes of all time. I wasn't aware that Vitor's cardio had a question mark actually. Very interesting twist to the fight.