Need to get some clarity on what you consider a "clip on", as for most a "clip on" or inline thermal means the thermal optic sits in front of the scope or daylight optic & the unit doesn't have a reticle ....
As for the AGM Rattler V2 it is a good entry level thermal optic, which is a hell of lot lighter than an Armasight (ATN) ThOR 320 2x Enhanced Thermal.
The "256" is the baseline option & will have limitations primarily with range/distance, whatever optic you pair it with is not more powerful than the "256" range. Also, latency & refresh rate are the biggest issue. The higher up you go in numbers & $$$$ , the better the refresh rate.
You gave a price of $1K, and "C 256" which means it is the 19-256 (don't know of a clip on in 25-256), but for the 19 , 1000yd is its limit, so you'll be good, but the Leupold VX 5 1-5x24 or 2-10x42 would be the preferred model of scope. However, $1K for that model is high, when Full Retail is $950 , may want to shop around, I've seen those for as low $789
Also, be sure using a thermal, even in daylight, is legal in your state.
We have the Rattler V2 35-384 rifle optic, so it has a reticle
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And I've had a bit of time behind a ThOR 320
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The ATN TiCO would be my preferred choice , better VOx , but I am also biased as I have more experience with ATN products