I am running FW 5.5.160 build 210416 from the US site. This was previously erroneously mislabeled on the site as old firmware, with the older version 210108 as current; which was confusing. Hikvision has now corrected the labelling error, and 210416 now shows as most recent version. The light linkage works, but as diesel and others report, the light comes on 7x24, regardless of daylight / ambient light, and no apparent way to change this. Annoying and not at all desirable. Maybe this functionality will get improved in a future FW update. In my case there is enough ambient light from streetlights so I don't really need the supplementary light, so I have just disabled the linkage option.
I have a pair of cameras covering a driveway. One is this 8M Colorvu (4 mm) and the other is an 8M Darkfighter (4 mm, DS-2CD2085FWD-I, already discontinued), so I have a good basis for A/B comparison. The Colorvu seems to have a significantly better image quality at night, and I think will be my new standard, and no longer use Darkfighter.
The picture seems pretty sharp and I haven't decided yet whether to try to take it apart and tweak the focus any further as others have done. I have several more of these cameras on order, and will compare the sharpness of them all once they arrive, and decide from there.
The cameras all feed to Synology Surveillance station in a NAS box, which I am pretty happy with. All detection is done in camera, not by SS. Synology doesn't yet support this specific camera in their device pack, but it seems to work well when I specify a similar Hik camera model instead.
I am trying out H265+, and seems to be working ok with much lower network traffic and much smaller file size.
Hope there is something in here of benefit to others. Thanks all for any comments.