The other big challenge I find with digital kit of all types is that once you get to a certain age every thing goes fuzzy, and you need to find your glasses to find the tiny little buttons to turn them on. And if your fingers are cold, had injuries etc etc those little lumps and bumps cannot be felt.
So you need to carry a pair of glasses. If, like me, you are getting long sighted, you don’t need them for normal viewing. There for they have to be carried - usually in a pocket, and that crunch you heard as you laid down - yup that was your glasses.
Beauty with glass is that most will accommodate pretty poor eyesight and as soon as you look through you have a lovely crisp image. If you zero your scope to shoot 4cm high at 100m, your bullet from vast majority of stalking cartridges will ne within 4cm of point of aim out to about 230m.
If you know what a deer looks like compared to your reticle at 100, 200 and 300, you can very quickly and easily determine if the deer is beyond this distance and this need to get closer.
If the deer is close, then concentrate on putting that cross hair in the middle of kill zone, reading the wind and squeezing that trigger. If you need to think about wind on a live animal - it’s too far and get closer. I have chased enough wounded deer to know that longer range shots really don’t result in saving lots of time. Following up a deer that has run after the shot, or even worse run with an immediately non lethal shot takes a very long and usually pretty miserable time.
As for thermal helping to find downed animals, deer have a good insulated coat, and if very wet very quickly will get cold. And if wounded tend to head towards thick cover, again which can mask a thermal signature very easily. In my experience they always seen to fall into gutters or down between the rocks and covered by heather. If there is no uninterrupted straight line for thermal or light waves no detector will pick it up.
The only really good means of finding animals is a decent dog.