I'm with Craig. For all the pizzas I've seen come out of mortarless ovens, yours are definitely the best.
I'm looking forward to seeing what you can do with Caputo. Any chance you could try an IDY only batch? A non sourdough version would be a good comparison to the typical non sourdough Neapolitan pizzeria offerings.
Also, what size pizzas are these? With the oven spring you're achieving, I think you can lower your dough ball weight a bit.
Lastly, I can't tell from the photos, is the back of the oven insulated? This isn't hugely important, but I'd insulate the front, and, if it isn't insulated, the back.
Edit: I've been thinking about this a bit lately. I should have mentioned this when you were soliciting advice, but a chimney is a critical component in the thermodynamics of an oven. The chimney heats, draws air, and this air flow fosters better combustion. You're making beautiful pies, but if you want to kick this mortarless oven up one more notch, add a chimney.