To me they're used in different situations, I don't use goat very often. Not because of the risk, just don't really like it. I don't use Krug very often, around here it's one of those preps that everyone says, "When it's working you have to have it, and nothing else will work as good." Well, the thing is most can't seem to tell you when that is. It's one of those times where someone says that's what they're on, then you either make the leap or don't.
To me Krug is used in very low bite situations, cool, wet/damp and or dry slick. It's especially good when the track is harder, but the temp is low and it's more dry slick. Tends to be a really good time to use it in my opinion. There have been a few times where I thought back and said to myself, "Maybe I should have used Krug." It's one of those preps that has a lot of mystery around it. But, I tend to agree when it works it's hard to beat. Whether it has goat in it, I don't know. When it's not the right prep to be on, it tends to get greasy fast.
Since a lot of preps contain goat especially for Burris, it's just one of those things that I don't tend to use a lot of straight. I have it, as most everyone does. IF I use it, generally it's to mix with something else for one reason or another. On Maxxis it tends to leave the tires greasy before they even hit the track. ( I know this is for Burris) On Burris yeah it's got it's uses, but I personally wouldn't use it straight unless that was the only way I knew to make them work, which isn't usually the case. So I might mix it with another prep for Burris to either enhance the effects of the goat in it. Or if that prep doesn't have goat and you want them to fire off. Goat straight just doesn't tend to last the whole race on Burris, and it's much rougher on the tires.