Thanks Loren. Taking things in order...
Rab: I'm mostly a Rab fan because they sometimes fit me (I'm the thick end of XXL). Montane/Haglofs/Patagonia/Berghaus/TNF mostly don't. Plus, Rab being quite successful, I can actually try their gear in shops.
Shoes: As it happens I have a pair of light Merrel road runners, and I like them. So I was already thinking I'd see if they have something similar with a bit of tread...
Pants: That's a really good weight, but I expect they won't have my size. I'll treat it as a target.
Backpack: tell me about it. The Deuter pack, which has enough mesh to make a MLD InnerNet and enough padding for Ryan Jordan to sleep on, is very comfy and pleasant to use. And it was cheap. But I suspect the sheer weight of it takes a few percent off how long I keep going each day. It served me well for five mile hikes, but...
Windshirt: I do have a Cirrus, but it doesn't really fit (same slim cut as Boreas but no stretch). I'll try it if I can shrink a bit. Also I *really* like the Boreas, I'm a conoisseur of breathability and the Boreas is downright excellent.
W/B shell: I love the Neo, it does to eVent what eVent does to Goretex. But yes, I could drop around half the weight. I think, since changing shell jackets is expensive and I also want to investigate the whole poncho thing, I'll save that for later.
Knife: makes sense.
Water treatment: I got the impression there's not a lot of water along the trail to purify, you mostly have to find a tap. I'll have another look at the map. But chemical water treatment is very light, it wouldn't take much to justify. Perhaps I should put a little in the medical/emergency kit on principle, even if it's not for every day.
Compass: I do feel happy about the idea of a backup.