Thanks for the thoughts, they sound all too familiar! Yes, it does seem that waterproof technology still can't offer genuine comfort in milder/warmer temperatures, so I will still likely opt to get damp from the outside (rather than inside) - except when it is 'really' throwing down, anyway.
That said, the gore-tex Pro jacket and wicking+snug baselayer combo at least work better than my previous attempts, so some tangible progress at last. Not much different when climbing hills sadly, but quicker to become comfortable again afterwards, which seems much more reasonable than spending most of the walk in an oppressive fug. So I'd say it has extended the portion of the year in which a waterproof won't be a depressing prospect.
I'm hopeful that the snug baselayer will do similarly good things for the windproof and soft-shell too. That might extend the conditions in which those are acceptable, hopefully not leaving too many without a decent answer. Though the synthetic baselayer does stink quite badly after a few hours, so I might need a plan B if walking in polite company.