Thanks for that. My thought process has moved on. I saw somewhere that the weight quoted for sports shoes is 1/2 pair size 8. When I look at the size I would buy, size 11 they are at least half as much again. Which makes an old pair of (very comfortable0 road running shoes, Mizuno Wave 11s, weigh about 40g more each than these. I think I'm going to take my old road shoes for river crossing and around camp as its abetter use of the worlds resources to finish them off in a Scottish burn that chuck them out because I've got a better pair for Parkrun.