Can't think of anything worse than wearing any type of non-breathable gloves on a long ride.
On long rides I generally carry 3 pairs of gloves, two pairs of fingerless cycling mitts (different makes that have gel pads and seams in slightly different places) and a pair of cotton inner gloves which can be worn over the top of the mitts for extra warmth. Some combination of these will keep my hands warm even if they get soaked.
The big mistake is taking wet items off and leaving them to get cold. Body heat will dry most lightweight cycling items (base layers, arm/leg warmers, mitts, cotton inner gloves, etc) in next to no time when stopped at a control, either keep them on until dry or, for gloves, stick them up the legs of your shorts. There's always a chance of a sneaky radiator or even an open fire somewhere (at a control or a separate cafe stop).
Only on really cold rides (rides encountering snow - Elenith or The Dean in 2008) I've got some Altura Waterproof gloves that haven't failed to keep my hands warm (even when they get soaked from 15+ hours or rain). They don't dry out so quickly though, so I had to swap between those and my mitts/inner-gloves with the other pair drying in a jacket pocket (using my body heat).