I wouldn't go for a plasma for any heavy gaming. I love the PQ, but my primary TV uses are sports (hours of ESPN) and gaming (lots of 4+ hour sessions) and I had IR issues both times I tried plasma. I never got burn in--just IR that would go away in a day or two max of not playing that game or watching ESPN. But it was still visible during bright scenes in normal watching and drove me nuts. I'm also not a videophile at all so I don't really care about motion blur, black levels and all that stuff people on this site drool over. I care a lot more about just having a TV I can use however I want without having to worry about IR--especially since so much of my usage involves static logos and game HUDs. The people who aren't having issues are probably gaming in shorter sessions, mixing up content a lot more than I do etc. If that's your usages, maybe you'd be ok.
Buzzing I think it just in the ear of the beholder to some extent. There are faulty units that buzz louder for sure, and the Samsung's generally seem to buzz more than the Panny's. For me, my hearing just seems super tuned into hearing that frequency of buzz, as I've never been around a plasma that I couldn't hear buzz over dialogue from viewing distance (8-10) feet during bright scenes. My inclination is that I'd probably hear it on most of the units people have that they say are silent as my hearing is just super sharp for hearing that stuff--I'm always commenting on an appliance buzzing etc. and no one else can hear it unless they get much closer (if even then).
Just my two cents. Plasmas give a great picture, especially for the price range they're in these days. If you don't have a lot of static images in your viewing, I'd say go for it for sure. Buzzing I wouldn't worry about as I'm just in a small minority that's very sensitive to it.
But if you have a lot of static images--lot's of games, hours and hours of the same channel with a ticker etc.--I'd be very wary of plasma. Some do it and just ignore the IR since it's usually only visible now and then on bright scenes when actually watching stuff--or they just don't scrutinize their picture when watching stuff and thus don't notice it. But for the most part it's going to happen if you're playing the same game for hours every night or have the TV on ESPN all day like I do etc., so for that type of usage I just don't think plasma is the way to go, even with the superior PQ.
I returned the Panny UT50 for a Panny ET5 LED and have been very happy. The PQ isn't as good on blurays (especially dark scenes), but I don't notice much difference on sports and video games which is the bulk of my usages, and I love being able to use the TV the way I always have with no IR and having no buzz. Motion blur I don't much notice or get bothered by, probably because I had a SONY rear projection LCD set for several years before upgrading in January.
But to each their own. You can always try a plasma from somewhere with a great return/exchange policy (like Amazon) and use it for a couple of weeks and see how it works out in terms of IR etc. for your uses. That way you may end up with a top line PQ for a great price if you find out that you aren't getting any level of IR that you can't live with.