A 384 will probably work just as well for you as a 640 unless you're hunting where you might get a shot at longer range. One of the most important things to learn when using thermal is to identify your target, and higher resolution is a definite aid. What I'm doing with mine is hog hunting and shot opportunities over 200 yards are not common. I used a 384 for quite a while, and it was not that difficult to recognize hogs at ranges longer than I'd shoot at them, but a part of that was simply because of their behavior and the number of different sizes of animals you see in a group. Once you learn hogs, they're pretty unmistakable. But still, now that I'm using a 640 I like it and would not want to go back to 384 if I don't have to. So, your intended use might be a consideration.
I've had the AGM TS35-384 and it's a good scope. Now I use a Pulsar with the 640 sensor and it is great. If I was made of cubic money I'd have one of those $16,000 Irays (or whatever they cost).
