Yeah, that's the thing with neoprene, at least the ones I have as well. Mine aren't the same as Colin's, but they're also not waterproof... I guess it isn't "closed cell" neoprene. My SIDI's also fit so snugly that even wearing a thin pair of wicking socks + the neoprenes makes for an uncomfortable squeeze (which then results in chilly feet). I could easily wear them in my Shimano shoes, but because they're so padded (skate shoe style) when those things get wet it seems like it takes days before they're totally dry.

I'm either going to get some better booties (mec packcloth ones work decently, but they look ******** and also mine are starting to disintegrate at the seams) or invest in some winter cycling shoes.