Man this posts makes me ready to get in the blind! I am in northen MO so your late season muzz and ours is about the same style of hunting.I can tell you from personal experience that it's easy to shoot the "wrong" animal (in my case a whitetail) when it's a first/last light situation. Happened to me a long time ago, and didn't matter much at the time...it was a legal buck, on public land, and the only person disappointed was me.
I have a friend in Alberta who is an outfitter in the Upper Peace River region. When I first met him I was a client hunting for WT. He highly discouraged taking shots at first/last light. His experience showed that almost all the bucks shot in that time frame turned out to be far smaller than it was thought to be, and often a good bit smaller than the minimums being targeted.
I hunt Iowa's late muzz season a lot, and it's nearly always an afternoon sit only. Unless the conditions are really good, meaning cold, bitter nasty, and more cold, the activity is usually the last 30 min of light. I've had property there for years and have shot a wall full of mature bucks, so I get a lot of enjoyment out of taking a friend and sitting in a box blind to film or just hang out. So far on the two shot opportunities we've had, both times the Hunter has swapped out his muzzleloader for mine b/c he didn't have enough brightness with his scope to pick out the right deer and make the shot. Their choice of scope will remain a mystery, as I don't wanna rag on any company in particular.
Regardless of what glass you have, light will fade to the point of not being 100% sure that an animal is the size u think. The better glass simply makes that window more favorable for you.
Most of the time, in a hunting situation, it won't make a bit of difference if u shoot an animal using a $99 Walmart scope or something that costs as much as a used Honda Accord. But at low light the better glass totally earns its higher price tag.
If my eyes were as good as they were 20 years ago I wouldn't be considering new glass.
Not all eyes are created equal. My wifes family all have exceptional vision. Like crazy long distance spotting abilities. One of my brother inlaws
can count deer out in fields while driving down the road. Even on very dark nights. I have been with him and he would say there are 12 deer out in that field pretty sure all are does. I call BS so we turn around and sure enough 150 yards out in a field there they were.
When my 12 year old can take a 6 power range finder and call out hits on paper because I cant see them on 9 power on an old Leupold...
and he can't either(using old Leupold) I figure its time I upgrade. I also have hit the rule of 80 and will retire in 2 more years(maybe one).
So after 30 years of making sure everyone else(kids and wife) has the best we can afford I figure I better get me a "retirement scope".