Well I decided against any more wort additions to the starter. The growth I've seen from this is convincing that 1.5 liter is plenty. I've plated it a few times and it will totally overgrow the plate after a couple days. I'm starting to think the only way I can get a sample banked is to keep it in distilled water.
Anyway here's what I saw as I opened the starter to pitch:
So I turned the stirplate on high for a second and stirred up all that goodness:
and the smells that wafted out were amazing! Fruity, bubblegum, marzipan, some other things that I have no reference for. Totally and unexpectedly pleasant.