A point nobody has made yet ... the S-shaped airlocks eliminate the contamination risk because they can bubble in both directions without pulling liquid in.
except that when they bubble 'backwards' you are pulling unsanitary air into your fermenter...
I am totally splitting hairs and would never actually worry about that.
I think that happens when any airlock sucks back (I guess not with blowoff tubes though). But I guess "eliminate" is too strong a word. Might just maybe eliminate some contamination risk possibly sorta.
