I think mcCain will still have an edge even though he would have less time preparing as he flew to DC and here's why?
Both , no doubt had 20 handlers practicing & rehearsing with the candidate.
Obama, though with a quicker , younger mind is well-known to stutter with,"Ah's" after every few sentences. He would flunk the toastmaster! He is not great without a teleprompter.
McCain is frankly kind of dry & boring in his speech, but at least does not stutter like Obama. I expect the questions asked Obama will not be too tough. Someone will ask him of his health & age.
Obama would have a tougher time handling questions on hypothetical terrorist attacks, Iran, whether he will negotiate with terrorists.
McCain will have a harder time in justifying the Iraq war, being an unpopular war with most Americans. He will have an advantage if they asked about the success of the surge.
If I were McCain, I would hammer the fact that the terrorist nations, Lybia, Syria, et. are cheering for Obama, who are they more AFRAID of?
McCain need to be MORE aggressive & be in control, and add a sense of humor, like Reagan. He is no Reagan, when it comes to communication skills.
I expect Obama to do a better job in closing statement since he could MEMORIZE that part.
Gov. Palin needs much work to polish her skills at answering questions. From my experience, it can be very stressful not knowing what questions they might throw at you.