I have also reduced all settings to 35-40 and watch the SD/HD channels in Zoom 2 mode, infact now liking them so much that willing to keep them ON for some more time.
FYI - I have seen E550 demo yesterday and the brightness looked good. It was playing SD channels in the showroom against all other Plasmas/LEDs playing demo video. Also the aspect ratio was such that the picture looked stretched (may be 4:3 etc).
Interesting, brightness is good on that TV. Regular SD channels are 4:3 which get stretched to 16:9 even on the Panasonics..