Sounds great, Bob! Always thought that red and black H-Bike in your avatar was an All MTN, but then again, I forgot that they employed that paint scheme in a number of E-MTB's for that model year, including the Full-Fat Six.
Oh, that job was completed in July 2020 and I have 2 thousand miles on the new components, with no issues. My immediate problem here is that a very good local bike shop closed their doors about 3 years ago now, so any other shop is a good ride and leap of faith that they are going to do as good a job as my late, latmented trustworthy shop used to provide for me. So I figured it can't hurt to try my own repairs, within my abilities and with the help of youtube.
Your issues about finding scarce choices to upgrade is part of the reason why I stuck with the original gear ratios and parts (Shimano XT) on my H-Bike. And now, with the parts supply chain in rough shape, it has to make it triple hard to locate components. Fwiw, that rear Shimano cluster is all steel.