Picked up a genuine bulb off ebay. More because I've been in a holding pattern on an upgrade.
I had not noticed any drop in my old bulb. It was at just over 1800 hrs.
The results were pretty staggering. Light controlled room, measuring lux on my phone. Moving phone around screen in same pattern, used calibration disc on 100% white pattern.
High lux reading, min lux, color mode, lamp mode:
520, 264 dynamic high
420, 258 dynamic low
240, 144 thx high
227, 98 thx low
1008, 489 dynamics high
650, 303 dynamics low
415, 189 thx high
303, 146 thx low
Numbers shouldn't be compared to other projectors, as this is a non-calibrated unit, tweaked to my color/lumen preference.
Numbers are good for comparing the bulbs though.
Moral of the story - you may be more ready for a new lamp than you maybe realized.