I hunt wide open plains for coyotes. If I was hunting more a mixed bag of terrain plus potentially hogs, the XL would be my first choice. The other factor is budget. The price of the XL is considerably higher as well. I killed 552 coyotes last hunting season with a 640-resolution thermal. Is 1024 a better image, yes, but the animals don't know which scope I am using when my bullet hits them. Upping the XL60 from 1.75 to 2.5 does make it more compelling for coyotes, but I do like a little more magnification.
How many pixels is necessary to get the job done? Not all 384, 640, 1024, or 1280 sensors and scopes are created equal. A saying a hunting friend of mine used to say is 384 is all you really need, but 640 is all you will want if you look through it. The same can now probably be said for 1024 or 1280. However, with all that said make sure you are using a thermal that will allow Positive ID (PID). If you can't PID your target, DO NOT SHOOT!