I've used LU many times (well, up until they started stalling out between
platforms for hours on end).

Hours on end ? Must be a different Underground system to mine.

That said, trying to manage more than carry-on luggage through the tube is
similar to trying to manage luggage on a bus - there are easier options...

It all depends on if you are paying or your firm, and how 'light' you
travel ! I never travel with more than I can comfortably carry, even
when I travel around Europe for 3 weeks plus. It's usually a rucksack,
a daypack and a plastic bag.