By comparison the stats can make the 45/70 or .450 look "sad" but don't think for a second that either of these calibers are weak by any means! And really, who wants to pack a huge gun like the .338 or the .416? I mean if you are hiking or heading to a fishing hole you want to be as light as possible. Thise are great guns, but fir packing keep it small.
If you plan to reload the 45/70 up to a hotter load, IMO you would be better served with a .450 personally I went with the 45/70 as I liked the stainless option as I hike to fishing holes and wanted to get away from rusting.
As for the reliability of the gun, mine is a pre remy, I have put several boxes of shells through it and it has never given me any sort of problem at all. Unlike the Winchester .450 I had for a short time that would jam one shell out of every 3 when cycling quickly. I loved the power of that little gun, but just wasn't reliable.