While this is technically sleeving, it follows Pieper's monobloc patent. Of course you don't end up with a monobloc... The advantage, as you have recognized, is increased strength in the chamber area. Like your Greener, the Husqvarna has a greener cross bolt, which gives me some comfort.
Rich and I went round for weeks about the cartridge. I finally decided after a long call to IMR powders. I use 3031 in other guns, so I always have a supply around.
The final load develops a bit more pressure than the 45-70 trapdoor load, but does not have the recoil of an all out 45-70 load. It is very close to the handloads I use in my 45-70 Marlin lever action. So in effect, when I load for 1, I can use the loads in either gun. Something I like.
The 45-70 is easy to reload here. Components are plentiful and inexpensive. The large caliber makes for a great boar gun. Solid hit to the lungs and they drop. In a couple of years, I will have enough points for a Wisconsin black bear license. The double gun will get a work out on that hunt.