I'm not sure that any are cleaner than the other. 7828 would certainly be the fastest burning. The thing is there is so much powder being burned with this beast that potential for fouling is certainly there.
This is a "gut feeling" but BMG may be a bit less "spikey".
It's funny how when you see some guys talk about the 300 rum one guy hates retumbo and the next guy loves it.
Here is another site to study with pretty good data on the 30-378