After years of using thermals I have come full circle on how I use them. I used to go for detection with the scanner and better resolution in my scope for the shot. That being said, I finally realized that I spent HOURS looking through my scanner and only used the scope for a FEW minutes. Lots of times I needed to use the scope for better resolution and it was in the rack of my ATV or not turned on, or the observed target moved out of sight, etc.
With the evolution of 12 micron 384 cores and thermal software improvements I found that they give me plenty of detail for shot placement. If you shoot longer ranges you also get a higher native magnification with a 384 core vs a 640 core using the same lens and lens size is a large cost component. I enjoy my time hunting more too since I can see more detail of everything I am viewing with a higher resolution scanner the entire time I am out in the woods. It also saves me the hassle of getting the rifle out and having to use that scope to ID the target as viable or not numerous times.
Like many other aspects of hunting it depends on your style and quarry so in the end it boils down to personal preference. IMO, probably the most versatile unit would be one of the new dual lens scanners with a 640 core. That way you get to "zoom" with the native resolution of the core and not have the pixel degradation associated with electronic zoom and you have a dual FOV choice for different hunting ranges.
Gook luck with your decision.