I have a 5 speed.
I would only prefer a 6 speed for closer gears and for that big 6th gear for cruising.
Even a honda civic Si comes w/ a 6 speed... but not my Boxster. Go me.
Whoever said there is a big jump from 3rd to 4th/5th is right. I never even downshift to 4th gear because it's so slow it is absolutely pointless.
I've never driven a 6 speed Boxster but I could only imagine...