The media has to be able to expand into foam, which is the low-tech equivalent of bubbling air or O2 through the media.
Yes, bubbling air or O2 through a diffusion stone is the alternative method I was referring to.
The maximum cell density for 5 gallons of wort is roughly 3.8 trillion cells; hence, pitching 400 billion cells requires log(3,800 / 400) / log(2) = ~3.25 replication periods. Pitching 200 billion cells requires log(3,800 / 200) / log(2) = ~4.25 replication periods.
Do you think there is any discernible flavor impact from that extra replication period?