I'm glad I'm not the only one who can't understand your nit figures
Can you give details of exactly how you are measuring nits? The way you present the info frankly makes little sense as you don't state the projected image size from corner to corner for the two ends of the zoom range, and nits only make sense in the context of a specific screen size of a specific gain, and would be measured off-screen.
If you go back to first principles and assume you have 1700 lumens (you won't once it is calibrated and you would have to be at maximum zoom for max light output, but anyway) and a screen that real world is giving you 1.0 gain then to get 460 nits your effective screen size for 16:9 must be only somewhat less than 70 inches diagonal? And no-one is projecting that small.