I knew I saw the term "vitality starter" somewhere before. It wasn't on Marshall's Brulosophy site, which is actually a very nice source of information, I think it was actually in the Water book. Now that I see the definition of a vitality starter as a starter that is essentially run for a very short period of time rather than being a very small size, the term makes a little more sense. Yes, the health of the yeast will go up when pitched into a starter if they are not given the chance to exhaust the carbon source. However, I think all starters should be "vitality starters" in that they should never be allowed to completely be exhausted of a carbon source and the focus is supposed to be on creating new healthy cells, not fermentation. I typically run my Saccharomyces starters for 18-24 hours on a stirplate, and my Brettanomyces starters for 48-72 hours. The viability is always quite high (probably because I'm often propping from colonies and all the cells were essentially just produced) and the vitality I would think is very high given the very quick start to fermentation I usually see (vitality is, however, very hard to measure quantitatively).
That brings me back to the higher cell counts for home brewers as a value added proposition. Let's say we have a 100 and 200 billion yeast cell pack, both 3 months old or 32.6% viability. Therefore, they contain an estimated 32.6 and 65.2 billion cells respectively. Let's say we're shooting for 360 billion cells. In this case, one would need a 2.2 L starter (1.037) for the 100 billion yeast cell pack vs. a 2 L starter (1.037) for the 200 billion yeast cell pack. That's right, another 0.2 L of water and 0.74 oz of DME will get you the cells you need from the 100 billion yeast cell pack as compared to the 200 billion yeast cell pack. Perhaps there is some value added if the yeast is incredibly fresh, but that value proposition fades with every passing hour beyond the packaging date. Even then, if using the exact same example as above except each pack were 97% viable, the 100 billion yeast cell pack would require a 1.75 L starter and the 200 billion yeast cell pack would require a 1.2 L starter. So, in that case still only an extra 0.55 L of water and 2.05 oz DME to get the necessary cells. All calculations were done on
this site.