My ewes wouldn't touch any nuts that get wet, if its raining when I feed, the next day I usually notice a load of uneaten 'porrige' in the troughs, so I wouldn't put soaked sugar beet in.
Can you buy sugar beet very cheaply? Last time I checked it was pretty much the same price as ewe nuts, and given the choice I'd def go for the ewe nuts! I have fed unsoaked sugar beet to dry ewes without any problems, I'm not sure if I'd want to feed to ewes in milk though as it would mean they'd need even more water?