My engine see's 7,000 rpm several times on each outing. I use my boxster much more for fun than transportation. Driving the car nice and easy just wouldn't be prudent.
The engine has actually seen 8,000+ rpms a couple times(doh!) thanks to over zealous shifting on my part but I've never heard so much as a whimper come out of it. The flat 6 engine seems to be able to handle hard driving with the best of them from my experience. I wouldn't worry about damaging it because it can probably take more than you can dish at it. Just be sure to it is warm before you flog it hard as the other guys said.