Keep in mind if you go OLED the picture will not be as bright, OLED is a negative if placed in a bright room. I would read reviews on it first, some OLEDs suffer from lack of detail in dark scenes as well.
But still a superior picture for a darker room, to me, it just seems the negative outweigh the positive but maybe that is because we could never go OLED, we have a bright room, roughly 18 feet of tinted windows 5 or 6 feet high for each with 16 foot ceiling and no curtains that face west. The Sony x900 series handles it with ease. Not that we watch TV at that time of day, except if there was some weekend event going on, but it is much brighter then even the Pani plasma that we replaced.
OLED is for darker rooms for sure.
He already has a plasma, OLED is brighter than plasma, no?
Personally I do not like bright screens. I have a cheapish LCD I put in my garage and I had to turn it way down, lol.