Just my two cents on this:
1. Burn in is real, it does occur.
2. Knowing about burn-in and being aware that it may occur is the best way to ensure that it will NEVER occur.
I had a plasma for years. Both a Pioneer and a Samsung, and I played some video games on them. But, after about a 4 hour run, I would turn it off and watch TV for the rest of the day. I could do this forever and I never had any burn-in issues. Why? Because I mixed up the content and was aware of what I was doing.
If I were to buy it exclusively for gaming, it might be another issue entirely.
Yes, OLED rocks. Period. It's the best looking display... period. But, it isn't perfect. Both brightness and burn-in are some real concerns. The black levels are second to none. The pixel response time is faster than LCD, but not as fast as plasma was. Oh, and it's a bit pricey.
But, at the end of the day, LCD often wins out because it really is quite nice looking and a fair bit less costly to get 90% of that image quality which OLED delivers.