Burn-in isn't an issue. Unless of course you're a complete numbskull and abuse your television with a static image set on Vivid for three days. I'm guessing you're not one of those people though.
Yes, go with plasma. You'll get a better image - color accuracy, black levels, motion, etc. You'll get IR, but it's not big deal and goes away after a few minutes most of the time. As long as you use common sense, reasonable settings, and use the pixel orbiter, you'll enjoy a natural cinematic image from plasma. Enjoy.
