all the player has to do is be at the door frame and he'll be able to instantly spawn into safety, nuze
and if people were to change classes it would take more time because you would have to switch twice
think of it this way, lets switch the class from a soldier to a medic. we push with lets say 30 ad.. i drop the medic to 20 hp he could have about 85% uber charge and he just preserve his uber back using a quickloadout bind RIGHT AT THE DOOR FRAME and he's able to get uber as we're fighting his team.
if you're saying that its the same thing as just switching classes the medic wouldn't have that 85+% anymore would he?