james, I think there is a significant advantage to the 445 over the 45-70.
First, it drives 300 grain bullets to circa 1800 fps with 1/4 less powder than the 45-70 takes to do the same thing. Most folks are pretty enarmored with 300 grain bullets at that speed, so why pay the extra price of powder and recoil to get there?
Second, While the 45-70 is touted as handling heavier bullets, I don't think a lot of target shooting is done with 400 grain bullets at speeds of 1700 fps +. In fact, I think many who shoot a lot prefer bullets weighing 300 grains or less, this is where the 445 shines, it drives bullets of 180 to 300 grains to within a few hundred feet of the 444, naturally with less powder, less recoil, less blast, all of which lead to shooting more and more enjoyment of the shooting.
Granted, if 300 grain bullets at 1800 or so is all one is doing, the 45-70 is as good as any and it will handle much heavier loads. But after this season, my 45-70 barrel will be mostly gathering dust, I didn't find it to do anything I don't get from my 44 Mag (How's that for herasy?)
now would I prefer a 445 to my 44?
I may have to get a barrel to resolve that, I like my 44 so well I just don't want to change it.