I don't think anyone here is going to try to hard sell you on the evo. If you love the pre, and you're happy with the total package (hardware and software), then don't upgrade. That said, as a pre owner, I can tell you I am far more productive on the evo than I ever was on the pre. There's no comparison in the number and quality of apps.
One thing I didn't see anybody mention, is if you hold down the menu button, you get your 6 most recent apps, which if you're multitasking means you can jump back and forth between email and nav in two buttons, which is one less movement than on the pre (swipe up/button, swipe left or right, click on app) vs. (hold menu, click on app).
I also hope HP/Palm brings the heat with generation two devices, but for a sprint customer on the premier plan, you're not losing anything by taking a year long vacation to let them get it sorted out.