Lets see here, 40 miles on the current bike, a 3 speed IGH, fairly heavy, managed to ride 3 miles the first time out after chemo series, and is interested in something that performs a little better. You as said above, have the bicycling bug, and are doing quite well with your riding, too. I had thought about your post while riding today and one reply mentions it, could you upgrade the rear wheel to say an 8 speed IGH, or even one of the Shimano Alfine 11 speed hubs?
Best of luck with the search, you seem to be doing a darn good job of research and getting things sorted out at the shops, too. Again, I'm glad that you are joining in here with us.
Bill