Would Ir illuminators give me more detail?

Haha. Can't you just solve that problem with camera settings? Like faster shutter speed? Then you've got better sharpness on a moving person and probably less noise too.
I guess so yes but then it's too dark in the background. Everything is a compromise!

It would be much easier if these settings were in the NVR.
 
Arguably, what is in the background does not matter as much.

If you are like me, you have several cameras looking at all the most important areas anyway :)