Well, there are two factors which lead me to believe that a mix of cameras may make sense. For the backyard where there is little nighttime illumination a 2mp Dahua Starlight camera makes perfect sense, but maybe for the driveway, where you leave a light on at night, and where there also may be streetlight illumination, and where a high daytime resolution may be very valuable, maybe this is a place for a higher resolution camera? Is that a valid thought process?
UPDATE-- I've ordered an IPC-HFW1831E to play with.
@davej as @aristobrat talks to, light can be a funny thing when entering the sensors of some of these cams. There are times when you think, WOW there's a ton of light only to find the resulting image is terrible and others when there's no light that cams such as the Dahua Starlights find it anyway and present a usable image. The real question is do you have an image or a 'usable' image and those 2 are very different.
You really do need to play with the area you have. The 1831 is a great cam. I will upload some night images from the Lorex I have that is similar to the 5831 and also the 9232S which 'appears' similar to the 1831. Will also post some updates when I get 2831's from @EMPIRETECANDY for comparison of a driveway lit by 3 x 1650 lumen daylight bulbs. Will also show you a wide area with 2 x 120W's and lastly a 3rd area that has no light (except overflow streetlight).
As @aristobrat stated, the technology is certainly getting there but still the Starlights (or Darkfighters if you are a Hikvision person) have the edge. A number of us are hoping for the 1/1.8" turrets (ideally with audio too) to be released and hopefully @EMPIRETECANDY Andy may have some news in April for Q2 releases using this sensor.
For now, using 4K where you have ample light for a good, usable image or as an overview + Starlights / Darkfighters etc as additional (ID) cams at entry points (doors, gates etc) is generally the consensus on way to go. The conundrum is right now investing in more 1080p Starlights or waiting for whatever Dahua releases next, luckily April is not that far away. As everyone else says here and I must admit I am now seeing too, this is an expensive hobby !