I once spoke to Dave Higginbottom(?), the late proprietor of "Lonestar Rolling Blocks" about the purchase of a rifle. He asked what I wanted it for and I said for hunting and for CAS. He then said - "Then there's only one calibre to consider - 50-70."
I asked why and he gave me the reasons I mention in my original post on the topic. Then he died from an unfortunate gun accident and I ended up ordering a Shiloh carbine instead. On their recommendation I ordered it with a 24" barrel as opposed to the usual 22". That proved a wise choice.
I also have a Shiloh Military Rifle in 50-70 so I'm well armed indeed. That was my favourite hunting rifle for years as it has sling swivels. It took me two large black bears and a 6 pt Mule Deer.
I'd still like a RB in 50-70 as I like the simplicity of the action. I do have a RB in .43 Spanish that I "sporterized" by having the barrel cut to 30" and shaping the forestock to resemble a Trapdoor carbine. I though about having it rebarreled to 50-70, but it shoots so darn well I can't justify it.
"If'n it ain't broke - don't fix it."
As for gittin' old, tell me about it .... it ain't fer wimps, that's fer sure.
A bone scan just told me that I have a deterioration of my lower spine that causes leg problems. And my PSA level has dramatically risen indication that the "Big C" has likely metastasized after nearly nine years of remission.
Every day is a bonus and a gift to be enjoyed.