The IMX291 is newer backlit sensor with much better technology behind it, it outperforms the IMX185 when it comes to sensitivity and thats why its a 1/2.8" Starlight.. if/when they extrapolate these backlit Starvis sensors to the larger 1/1.9" format it'll fucking destroy the IMX185, its just a matter of time now.
Ive got both, and the IMX185 is not that much better than the IMX291 for most situations.. What makes the UltraStarlight kick ass and worth the premium is not how much better it is at low light over the IMX291 (though it does contribute), its SSA Backlight feature, Image stabilization for pole mounts, and vandal resistance; your not getting that with this pice of crap camera.
Authorized my ass, they are not listed as an authorized distributor on any of Dahua's sites.. thats why they put there own name on em.
Note this company gives you Lux rating for a lens it does not provide; asshat move.