This whole dry yeast cell per gram thing is odd. What is the basis for 20 B/g? An old exchange between Dan Listermann and Dr. Cone, Zainasheff references that same conversation and his own cell counts (plus the cell counts of other, with no references) and Sean Terrill's viability experiment.
I think Ockham's Razor applies here: you have to make a ton of assumptions for 20 B/g to be true:
1.) Dr. Clayton Cone WAS NOT talking about wine Yeast.
2.) JZ's innumerable cell counts were valid.
3.) Sean Terrill's cell counts were valid.
4.) Dry yeast manufacturers give you 300% extra cells because they assume you won't follow directions.
On the other hand, you do t have to make any assumptions to trust the manufacturers technical specifications.
I say this knowing that I have never count dry yeast cells, which is something I may do here soon.
I of course could be totally off base here...