I've definitely had some trouble with S-04. I brewed an English Bitter and it had a very tart finish. It has that nice round malty front, with a nice bitter finish then out of no where comes this tart I licked a sour patch kid or cry baby flavor. It faded as I drank through it and it aged in the keg but never went completely away. This was before I had temp control more firmly nailed down like I do now - but with so much other available yeast, dry and liquid if I get a yeast that doesn't perform well or suite my taste I just move on -- likewise if I get one I like for a particular style I stay with it. Don't fix if its not broken mentality.