650 Vs 700

I need some advice on the difference between 650 and 700 tires. I may be purchasing a tri bike that has 650's on it but I am not sure of the effect that they will have on my riding. I have been told that 650's accelerate faster and that 700's may ride a little smoother. Does anyone know the pro's and con's? Is there a size issue (I am 5'11'', 185). Any links to articles would be appreciated.

What lead you to purchase a bike with 650s?

650 are for small frames so at 5'-11" I see no real reason you should use it, besides a larger wheel rides better on average roads and always corners better
because it brings a longer contact patch to the road.
A longer contact averages traction over more pavement and avoids slip outs for lack of local traction

Alot of tri bikes were built for 650 regardless of frame size.

I have not yet purchased the other bike. I've been riding on a road bike with 700's for the past two years. I started doing tri's a few years ago and I've been adding to the number that I enter each year. The bike is a very good tri bike and it is about time for me to make a switch. A friend is offering it to me and I don't want to turn it down unless it is a very unwise move.