I like a 1X monocular in 640 core because you have a nice wide FOV for closer range work and looking for downed game. At longer range you can zoom to 2X and still have a nice image.
With my IR Patrol 19mm 640 core I find it great for scanning nice FOV and provides enough detail to ID critters 300-500 yards out for a experienced hunter no problem. The FOV of the Patrol often looks prettier to my eyes than my Reap-IR FOV to me. Sure the ReapIR will give you more detail at longer ranges but I would prefer the Patrol 1X as my main spotter 90% of the time.
With a 320 core I find a 2X works best for me even though it's Alittle less Effective scanning for downed game in tight cover with less FOV. That said a 1X 320 doesn't give much "detail" past 100 yards however with detect critters 400-500 yards out easy enough.