I'm sure the GP5000s are very nice, but perhaps too fragile for everyday commuting/shopping etc. use (or touring?). Hence why I was thinking of the GP 4 Seasons as a sort of compromise
You'd be surprised. I commuted through central Amsterdam all summer last summer on GP4000s ii in 28mm, only time I had flats was when I toured through Denmark, where the flints on the road were a total utter plague. In Belgium, France, and Netherlands, I had no flats at all touring and audaxing.
When I get a new job, I'll also be commuting on GP5000s in summer, with GP 4 seasons in winter. The difference between the two is noticeable. Swapping from GP 4 seasons to summer tyres in the spring is like suddenly taking a brake off.
J