And you can kill all of those with a .22.
Not ballistically similar to me. The .410 slug is way too light. It sheds its energy very quickly.
.44 Mag., 240gr at 1760fps - 1650 ft. lbs. ME, 966 ft. lbs. at 100 yds.
.410 Rem 87.5 gr slug at 1,830 fps—651 ft. lb. ME, 210 ft. lbs. at 100yds.
True enough, but in the thick stuff, you won't get anywhere close to a 100 yard shot.
25-30 yards max. (Thinking Missouri/Yellowstone River bottoms and willows here, the steep draws of the tributary coulees, or the dangnear jungle of greenbriers, honeysuckle and such where I grew up in MD) If I'm going to reach out to 100 yards and beyond, that is what the .30-06 is for, 180 gr. core-lokt is my favorite all around round, and the optics make it an easier shot. I have a tip-off mount and iron sights on my Model 70, so if the optics are off/damaged, I am still in the running.
Anything well wooded is pretty much open once you get back inside the treeline east of the Cascades, and most of the middles of nowhere I have been in up and down the Rockies, the Basin and Range, The Great Basin and in desert terrain are either wooded mountains or open prairie/desert or badlands. Line of sight is either very short or very long. In the Appalachians/Alleghenies things tended to be more grown up underneath the 'canopy', with second growth, deadfall, and a more humid environment.
Besides, as much as I like my Marlin, it isn't worth squat as a scattergun. If I'm hunting in brush, that's my go-to deer gun for the breaks, but we're talking a game getter, and being dropped off in the boonies.
There are a lot of trade offs. Power vs ammo weight vs number of rounds, versatility as a game getter, utility for larger game/problem predators, and range. I have taken whitetail with a .410 (75 yards, I was 11, and my Dad paced it off--he kept track of everything to do with our deer hunts, data which proved useful in later years.), countless ducks, rabbit, and squirrels. I have taken whitetail (to 275 yards) and larger animals with a .30-06. Most game you get in the boonies will either be smaller stuff, or will be farther away, at least in open country, and the shotgun will do it. If people are a problem (overt life threatening activity with clear intent), that changes the equation. Back off for distance, and if they persist the .30-06 comes in.