My Mitsu Diamond 65711 is 5 years old, and I do have the shield on it. I have a brand new Panny 65PZ850u. I wrote a longer comparison earlier and walked away, it timed out, and I lost the post hence my shorter post above.
I think you really have to compare for yourself, but I have a little time now so here goes. I do not have either set calibrated, but I did find some settings for the Mitsu online and used those with some adjustments of my own. I also went into the service menu and did away with the red push on the set. So I did make some effort to improve the PQ, but after five years I wanted to free up some floorspace without loosing size or sacrificing PQ. I checked out the LCD’s but preferred plasma’s handling of motion and color accuracy.
Brightness is definitely not an issue with the Panny. I have four windows in the room and have no problem seeing the set even in the darker Studio Ref mode. You can brighten this thing up to near LCD if you like that look, but I would go with the curtains and the more accurate settings. The screen is no more reflective than the protector on the Mitsu. I have mounted it on a tilting mount and this allows me to compensate for reflection nearly getting rid of it all together.
I’m not using it for gaming. The Mitsu went to the basement with the 360. I don’t think you need to worry about burn-in as you have been living with a set that is more vulnerable to it than today’s plasmas. I never had any image retention, much less burn-in, gaming on my Mitsu and have yet to see it on my Panny. You may want to check out some plasmas and see if you are in the 1% or so that can see phosphor lag. I don’t, but apparently this is an issue some can see on plasmas.
The Panasonic seems to do a better job with SD content. This may not be relevant for that much longer but it is what it is. The OTA HD tuner in the Panasonic is better. I used to have to make antenna adjustments for the Mitsu to get all the channels I wanted. After plugging the Panny into the same cable it gets them all, and more, with no adjustment to the antenna. The viewing angle is much better on the new set, and IMO the colors are at least as good if not better on the plasma.
You and I came to a similar conclusion when purchasing a RPTV. I may not have all the words to accurately describe the PQ, but I know what I like. I have never had a set calibrated, but I do a lot of tinkering on my own to improve the PQ. The picture is excellent on the Mitsubishi, but I love the Panasonic with the 1080p Blurays. Football in HD is just as good as the Mitsu. Get yourself to a home theater store which has the 65 on display without all the fluorescent lights. Make sure it is playing a Bluray and set the picture mode to “Studio Ref” then decide if the picture is good enough.