I've got a bit of experience with both rifle types and several years ago I decided that I wanted a Marlin 1894/.44mag myself. Very nice rifle and plenty accurate for my needs; carry in the woods, deer and hog hunting. I found, though, that it was a bit lacking when I got an opportunity at a really large hog.
I ended up selling the .44 and bought a Marlin .375, which is pretty much the exact same size rifle-wise, but a good bit more powerful, IMHO. For the record, I now also own a GG in .450M. Anyway, I decided to take a picture of the rounds mentioned in the original post, simply for comparison purposes as I was pretty surprised that some claimed a .44 carbine would be just as effective as a 45-70. That's not my opinion, by the way....lol.
The picture below is a .44 mag 270gr load @ 1700 FPS flanked by, at left, a 400gr 45-70 @ 1900 FPS and a 325gr 45-70 @ 2050 on the right.