I think in any emergency situation everyones performance varies, nobody knows how they will go on the day.
I think what people would be hoping for is that in an emergency when the S hits the fan, that at least the basic (albeit robotic) training of crew will kick in. Not to say that any joe blogs isnt cabable of doing it, its just that sometimes reversionary training seems to help.
From many incident reports, we can see that even the best highly trainined cabin crew stuff up at times. We have also seen that able bodied passengers at times can get in the way despite their best intentions.
I think the advantage of having a crew member be it pilot or otherwise (aircraft and airline specific ??) in those seats would be an advantage. They would be in tune with the rest of the cabin procedures, the specific warning phrases that some airlines use to evaluate the situation, and the evacuation provisions. Also they may be more aware of the specific dangers of opening exits into external threats.
After having listened to conversations between frequent flyers, it is amazing with some of the crap they come up with about aeroplane operations and performance!