Even though the 2nd and 3rd generations were ready for transfer much sooner, the damage was done. The 2nd gen beer is lovely but has the slightest hint of warmth from higher alcohols. The 3rd beer is a complete mess.
To what are you attributing that differential in results? Stressed yeast from sitting in the fermenter? I'm not sure I buy that theory. I've stored yeast for long periods and not had off flavors from subsequent generations.
Just off the top of my head I would think that repeatability with subsequent generations of a mixed slurry is difficult since you can't control the proportion of the components of the slurry. I'm not intending to crap all over your experiment, so apologies if this comes across that way. Quite the opposite, I think those sorts of experiments are important for each of us to better understand our ingredients and processes.