I am hoping to brew a 1.068 Maibock this weekend. I am planning to use an L28 Urkel crop I took from a batch of Vienna I just kegged. I collected 350ml of thin slurry that I swirled back up into suspension after filling the keg. I was surprised to see that I only had 100ml of thick slurry after the yeast settled because I was fairly certain that I cropped at least a third of what was left in the fermentation vessel. It is pretty clean yeast. All I can say is that based on the what was left in the fermenter L28 Urkel has smaller than average yeast cells. At 75% AA, the batch definitely reached full attenuation. Until I conduct more research, I am going to adjust my fairly clean thick slurry volume pitching rates to be based on 2 billion yeast cells per milliliter for this yeast culture. I will not know for certain until I conduct actual counts. However, there is more thick slurry in my crop than there was in the Imperial package and Imperial claims 200B cells per package. I rack such that I leave nearly 100% of the hop particulate matter and at least 75% of the trub in the kettle. I do not dry hop, so what is usually left at the bottom of a fermentation vessel is mostly dead and viable yeast cells. I pitched the package of L28 straight into a primary containing 5.25 gallons of 1.056 well-aerated wort (I used my acrylic tube venturi-based aerator). L28 ripped through most of the extract in under 5 days at 54F. I raised the temp to 60F and allowed the batch to finish before lowering the temp to 40F.