I've heard plenty of people saying the GP4000S feels "dead" and the Pro3 was much more "lively". Is that still true of the Pro4 line, and is the flat resistance at all comparable now? The GP4k flats almost never in my experience (knock on wood) while feeling MUCH better than the Gatorskin. Still, I'm violently allergic to flats, so I'm disinclined to try the Pro4 unless they're very durable as well now.

Lifespan is less of an issue for me, mind you, I just don't want flats while the tire is in use.