If your letting it sit for 48 to 72 hours then you are just soaking (not fermenting it), cockers have been doing this with there oats for years and it most likely dating back 100 years or so.My feed is not highly fermented. Like I said, it sits for about 48 hours total. Maybe 72 at the very most.
I have been feeding the chicks 100% fermented and I've never seen such a fast feathering rate. Also haven't lost a single chick, and I usually do lose one or two in batches. Just my experience with it. My chickens have been dealing with the cold no problem. Here in Canada, we have lots of cold weather.
If I noticed odd behaviour (acting cold) I'll consider adding back dry feed. As of now - every thing I've seen is positive. They are more active, better feathering, eat less, drink less, lay stronger eggs with bigger yolks, have higher hatch rates from said eggs. Only negative I've noticed is with silkies getting it all in their beards.
Not saying you are wrong in your assumptions. Maybe I'm not noticing any of the negatives because the feed isn't highly fermented?
Chris