Interesting thread,I recently bought a 19" P7 (2010), I'm 5 11 tall with a 33 " inside leg.
I felt it was too big a frame with not enough stand over – didn't measure how much post was sticking out – but it looked enough. Just didn't feel right on it (lack of stand over , more than anything else). The P7 doesn't have much in way of a dropped top tube.
Since bought a new medium Cotic Soul – 250mm of seat post to the saddle rails, but feels much better (and definitely more stand over).
As others have said it depends on the frame and how individuals like the ride – probably the best in terms of fit that I've had was a large Turner Flux.