I use regular feed. The sweet feed is blended with molasses, which adds calories that probably aren't necessary. I also had a person who bought two doelings from us have a scare with goat polio that was due to sweet feed (too much molasses, I learned, can contribute to thiamine issues which causes goat polio).
I use the show master pre-mixed feed and was looking at a commercial sweet feed that is for "all livestock" which included goats. It said to feed 1 lb of feed/100 lbs of goat in addition to pasture. I have a nigarian dwarf and the breeder I got him from used to mix it in w/ his feed. I was wanting to add extra calories for the winter. I also have a fainter I'm wanting to breed. Is there anything extra I should start feeding her?
I recommend free choice hay, minerals, a daily ration of goat feed and that is all. The all-stock feeds might do in a pinch but do not meet all of the nutritional requirements of a goat (too bad too because they are cheaper). If you are going to add anything, increase the amount of available hay---the hay consumption encourages good rumen development and can produce a little bit of extra internal heat (kind of acting like a compost in their bellies). I have heard some say to give corn because it is a "hot feed" but that is a misnomer---it may have extra calories in it that give rapid energy (thus are hot), but they do not actually produce physical heat. Corn and sweet feeds might add on fat, which I suppose might insulate a bit, but fat can cause other issues and is really not necessary in order for goats to stay cozy in the winter.