has anyone used any of these that actually work well?

we have tried a variety from different manufacturers and when viewing back the picture level (depsite assurances of x amount of meters etc) is shocking at best. most seem to fall over at dusk / mid evening time

agreed.

The samsung unit seems to work well, but I have never fitted any.

In my opinion you need a seperate IR emitter. These built in leds are only any god for short range internal stuff

It's an unfortunate fact that some manufacturers like to build all singing cameras, although if the truth be told, the vast majority are seriously out of tune.

As redbull correctly suggests, using separate IR illuminators to produce optimised images will always be the preferred option, amongst those who know what they are doing

Have to agree as well, interally those with inbuilt IR are good but outdoors anything pasted maybe 5m, usually less forget it..

Even with additional IR lighting there is a limit to how far you can see anyway depending on what type of IR light you put up - spot or flood type.

Seperate IR

but if it has to be built in try Basson as theyre built in IR cams are quite good but not cheap