Which winter shoes / boots are people using?

Sure. If you want to spend that much money on a winter off road boot that's slippy and not very warm (which comes through in most, if not all, of the reviews I found), then you have the ideal boot. Also:

"very slippery on wet roots and rocks."
"They're not so uncomfortable that you can't wear them, but they're not exactly luxurious, either."

The fact that about £50 will get you a comfy goretex or similar vibram walking boot might throw some light on the value aspect of things though.

You know that you're supposed to be riding over those bits, don't you?