Hello,
I think it relates primarily to the glass. Any weight on the glass or torsion in the frame around the screen will crack the glass.
Therefore they recommend keeping the screen upright.
In relation to care and maintenance, burn-in is a real problem despite the new generation.
For example, I fell asleep for 30 minutes with the Foxtel (Australia's equivalent of Sky) menu up, on a current generation 507 Pioneer Plasma.
For several days thereafter, I could still read the Foxtel menu from the screen burn. I hate to think of how bad it could have been had I slept longer.
I recommend setting the T.V. to switch itself off in the Power Saving options after 2 hours (I think that's the minimum listed), if it has received no operation signals (eg. change of volume from T.V. remote etc). The signal from the DVD or SKY won't impact on this setting, as it only relates to T.V. operations/changes. You will receive a warning that it will power off 5 mins before. When that happens, just toggle the volume (on the T.V.) if you don't want to interupt your viewing and the 2hr timer will start again.
BTW, you will definitely need two people to move her. She's a beauty, but she has the weight of a beast.
Sincerely,
Robert.