I just bought some Teve Links Mids for £60 in Evans, similar to a light weight walking boot and plenty of toe-wiggling room. They arent waterproof, but supposedly arent as sponge like at 5:10s.
I've also got AM41s, they dont offer any real weather resistance either, but dry quicker than Impacts.
Apparently 5:10 do a waterproof boot/shoe designed for scrambling, which was recommended to me ("Guide" maybe), but I havent see them in the UK.
There's a gap in the market for a decent flat, winter boot with a good ankle cuff - I miss my Northwave Celcius since moving to flats.
But if it's cold and Reynaulds you're concerned about, I'd go for thick merino socks and an overshoe, and make sure your boots are loose enough to move around in. Good luck, my GF has it too, and makes riding hard in the winter.