>Also, I don't understand how having almost the same knockdown power at 200 yards that a 170 gr gives at 100 yards can be considered of little practical utility.
Well, then, you don't seem to realize the reality of how virtually 100% of these rifles are used. I would venture to guess, backed by 45 years of experience hunting deer in all sorts of terrain, that the vast majority of hunting shots fired at big game by levergun carbines are at 100 yards or less, and a very significant portion at no more than 50. I realize there are parts of the country where 200 yards is a short shot, but that's not most places, and the man who would choose a .30-30 levergun for such a locale is severly limiting himself regardless of what ammo he's using. I love my Marlins and use them all the time here in the woods of the southeast, but if I were going to hunt out west the Marlins would stay home. That's what my Savage 99A .308 is for, and it puts the LE .30-30 pretty far in to the shade..
There's no denying these is a slight advantage in trajectory with the LE ammo, but at the typical ranges these guns are used that is a moot point, sort of like having a 50 MPH wheelchair -- neat, but where are you really going to get any benefit from it?