Hi Iain
Your link has the very pair I use for my tubing.
Vision also did a 3.5mm pair but dropped them from there range either last year or the year before.
When we all head for the north west wer usually walk from loch to loch wearing all of our kit as it is only a few hundred yards from loch to loch.
We do walk about up to a mile in the waders, you can always roll them down to your waist while walking.
As soon as you get to the next loch, the cooling effect of getting back in the water is great, I might try breathables for the middle of summer this year.
I think it all depends on how often you tube and where the seams are on your breathables are, if the seams are not going to get rubbed thay may be OK.
I have no experience of tubing with breathables, but a decent amount tubing cold scottish lochs in my neoprenes.
I will try the breathables but feel that neoprenes are a better bet most of the time.
Kev.