What kind of humidity climate are you in? I would consult technical service from Pioneer and ask them if they suggest any sort of tweaks to the cooling fan system because if you are putting your TV in a more humid atmosphere the cooling fan may work too hard since there are already more water molecules in the air, depending on where you live.
I would like to move my 60" Pioneer HDTV (projection) to a covered patio. There is no chance it would get wet from rain, but obviously it will be subject to higher levels of humidity and heat.
I've had a 36" tube TV there for 2 years and had no problems.
Does anyone have experience with large TVs outdoors? Any problems?