Have used a pair of neoprene kayaking gloves for wet-weather riding -- similar to a diver's wet-suit gloves, maybe slightly better suited to cycling because they're pre-curved, with sturdy protective covering on the palms & fingers.
Don't have mine readily to hand, but they're about 2.5 or 3 mm thick.
Pros: keep your hands warm, but not really dry. If you used them all day, your hands wd be seriously pruned, I think.
Cons: as with all watersports gear, how to dry the things? Esp since you're wearing them 'cos it's wet, no? Ansd as you'd expect, they get seriously stinky if they don't get properly dried out.
I've not had much luck with waterproof-breathable over-gloves: they tend to be one or the other.
My wet-weather motorcycling solution is simply XL heavy-duty washing-up gloves over my riding gloves. But in that situation, I'm not generating much heat, hence not sweating.
For the moment, I'll stick with my kayaking solution. Surely there's a better arrangement--maybe a reader in Vancouver or the West Coast of Scotland or Ireland can offer one?
J.
