How can the group exit out of the first level? Was there a sedative timer in the plane that wakes them up? If that's the case it ruins the point of the story:
Eames says that "He's sitting this one out" because this is too dangerous.
Then Cobb is like "n hours of flight will mean x weeks" and I can guarantee we will all be dead by then to which he then suggests that they "continue on with the plan and use kicks"
Ahm Wait, you lost me there. Okay, okay, "use kicks"? Well if you have a kick in the higher level then it doesn't matter what you do right? You can just wait for the kick in the plane level. Then it's the same timespan.
To Clarify: How did they get out of the first level? There's no kick in the plane? If they couldn't get out of the first level, then its the same thing, they have to wait for the sedative. And it will just reaffirm Cobb's "n hours of flight will mean x weeks and I can guarantee we will all be dead by then"