I was amazed at the impact of the yeast. I had three FRSB (OBSO, OBSV, and OBSK) that I diluted down to 100 proof to do a blind tasting of. I don't know the exact age of the OBSV (this was a standard, retail bottling), but the other two were both 10 yrs + several months (3 months and 9 months). There are obviously still other variables (where in the rick house, wen distilled/bottled), but this was the best I could do with my stock to limit to just the yeast. My goal was to figure out which was my favorite (which turned out to be O - Robust Fruitiness), but I was amazed that I correctly guessed which was which based on the descriptions of the yeast (the K definitely had a bit more of a rye-spice character than the other two, and the V was fruity, but not AS fruity as theO). I don't know if I'd always be able to pick them out (tasters have good and bad days), but it convinced me that there is a difference. And most importantly - it was a lotta fun!