What difference did Luke make on Bespin?
Okay, so Luke sees his friends are in trouble in a "City in the Clouds", pisses off Yoda and OB1 by quitting his training and flies off to save them.
Before he can save them, he gets into a duel with Darth Vader, learning this was all an elaborate trap for Luke. Meanwhile, Leia, Lando, Chewy and C3PO make their own escape and only got in trouble when they had to turn around to go back for Luke.
So how did Luke's presence on Bespin make any difference in his friends' escape?