so let's assume the yeast is healthy enough to become active. how is "waking up" in 2-3L of wort better than "waking up" in 5-10 gallons of wort?
I'm a little late to the game but I wanted to add my 2 cents. I never do a vitality starter with 2+ liters. It's always like a pint or two.
If you did 2+ liters of starter, it would require a decant. I don't do that. I brew my beer, take some second runnings and make a starter with it. Then, I add the entire "starter" to my fermenter. Only after I can ensure that the yeast is viable of course.
It adds just a bit of volume to the beer, but since it's the same wort I'm not worried about any flavor contributions. I'm only worried about making sure that my yeast is ready to ferment.