I have the northwave boots, I brought them in the summer from
CRC for about £80.
I wire them on the wiggle rut. It started of about 2° and rose up to about 7°, but there was a fair breeze and the chill factor would be below those temps. I also wore wooly bully socks. My feet were a bit chilly, but never cold.
I dont usually do long rides in the wet, but so far when I have been caught out they have kept my feet dry. I thing that if you are wearing long tights then they will get wet and then let the moisture work its way down into your boots if they arte tucked inside.