I'm right there with you man... I had my Panasonic GT50 replaced due to severe burn in. I used my best buy credit toward the ZT... PQ was amazing, fan noise and IR were a deal breaker. Tried the f8500, didn't like it... no matter how much I tweaked the settings I could never get it to look as good as the ZT. Went back to the ZT... bad IR was the ultimate deal breaker... babied the set during break in period but it didn't matter still got IR that didn't go away.
Now I'm considering the X9 (sony 4k tv). Right now I have my samsung F4500 43inch 720p plasma that was in my bedroom in my living room... never babied the set, I watch cnn and espn for hours and no IR and no burn in at all... go figure. For $350 that little samsung is a damn good plasma, everything looks great on it.