My foldup bike as 24 inch wheels (507mm), with a 39 tooth chainring, Dual Drive, eight speed 11/32 cassette, my gearing ranges from 20.7 to 112.1 gear inches.

You are correct that the high end is less important to most cycle tourists, I am one of the few cycle tourists that continues to use a road crankset on a full size derailleur touring bike. My Thorn Sherpa touring bike has a 52/42/24 triple and eight speed 11/32 cassette, range is 19.2 to 120.7 gear inches, but my top two gears are only used for shallow long downhills or strong tailwinds on the flats. Most cycle tourists do not have the higher gears that I have.

I was more focused on your lowest gear, switching from a 20 to 26 (gear inch) low gear is something I would not want to do. I want a lowest gear in the 20 inch range or lower.

I use two different chainrings on my expedition bike with Rohloff. For around home use and on most road riding I use a range of 20.1 to 105.8 gear inches, but for off road where I never go very fast I switch to a different chainring which gives me a range of 16.5 to 85.5 gear inches.

But only you know how steep your hills are and what your capabilities are. So, I think you should go out with your existing setup and climb some hills in your 2nd, 3rd and maybe 4th gears and decide what you really think you need for your lowest gear. If you can climb all the hills you want in 3rd gear, then go ahead and get rid of the Dual Drive.