i went for the guide. I tried a few and as sauer said the refresh rate of this is way better than the 9hz of the flir. If you scan an area it is like a video, it does not jump as it is refreshing like a TV. I am not a boffin on these things so i am sure someone can explain this better.
It can see red deer at 1000mtr, roe deer at 4-500. It also sees deer that i cannot, and finds them even when my binnys cannot find them, say in undergrowth or through trees. I was out with some pro stalkers last week, who were initially quite sceptical about it. We went out and they quickly spotted deer i did not see, noting "look, one over there". I had a thermal scan and saw 4 and it took us ages to see the others, though eventually we did see bits of them.
For the rest of the trip i did not get my hands on it, and the boys noted that is could see deer we could not, but also that it is fast, if you scan an area and cannot see them, then they are not there.
You do need to understand what they are telling you however. I have used them in work since they came out so know them well. Basically they show differential temperatures so if you have a screen full of something very cold like the sky, then a small warm thing like a deer will not show well. Lower it and cut the sky out and then the overall differential changes and the deer will glow! They also never lie, so a hot thing in the clear fell may be a warm stone, but is probably alive.
They work best in the mornings, when the ground is cold, in the evenings hot rocks and tree stumps can confuse the user.
Mine has great battery life, is so small it is clipped to the binnys strap and has an output to a small screen/recorder, so everyone with me can see what is going on, so works very well for my use.