I have a quality thermal image monocular and I would like to mention a couple of factors you might not have thought and this is from experience.
Shortly after buying my T.I. monocular I was doing hippo PAC at night. The hippo were coming from the river, pushing through a fence and coming into a large mealie field. While scanning with the monocular I noticed how hard it was to judge distance and thought T.I. binoculars would improve my ability to JUDGE DISTANCE.
Second experience. I was doing elephant PAC on a cold rainy night. We knew the elephant were near, but the elephant were being very quiet (probably testing the air) we were staying frozen! On this pitch black night as only Africa black can be I decided to use the T.I. monocular. Aaagghh, one elephant was right in front of us. I quickly dropped the monocular and went to my .470s sights, they were no longer there!! The monocular which I used with my right eye had ZERO NIGHT VISION. Now I am smart enough that if I use the monocular at night I use my LEFT eye. If I had been using thermal image binoculars I would have been totally blind.
Fortunately some times "Dianna, goddess of the hunt" takes pity on fools, I am living proof!
Keep in mind I am talking about Thermal Image, not passive night vision devices, those I have had good luck with!