The Mille Alba sounds great but too much for me and not just the highland midges.
I’m very happy with the TSR30 gear range. Even on reasonable climbs that don’t need the really low gears that feeling of “several more lower ones to go” is very comfortable.
We did a Xmas 50 yesterday on the tandem the second half with 9 gears (middle ring only) due to a cable breakage. Easy enough for a short distance on local roads I know very well with an 11-32 cassette but I wouldn’t fancy ploughing on into unknown territory without the granny ring. Perhaps I should carry spare gear cable for the TSR as the 11-25 would be a bit limited locked in middle ring.