Same here. I don't really like his yeast calculator.
Why not?
Two main reasons. 1) As far as I know, he never actually published his data. 2) His growth formulas don't line up with what other researchers, or homebrewers have found.
I prefer the models based on Kaiser's data. In particular I use the one over at brewunited, which has a built in support for harvesting yeast from the starter.