Mark, thanks for the detail reply and pics. I'm sure it will help others wanting to replicate your results. So it sounds like you bake on the bottom soapstone and then set the pie aside, move the soapstone higher up and broil to finish?
Happy to do it Chau as people here have done the same, it's the least I can do to give a little back

As for the baking setup, I heat up the stone on the lower rack for an entire hour, then I move the rack/stone to the top rack and hit it with a broiler at 10 minute intervals trying to shove as much heat into the stone as possible. Once it's on the upper rack, I don't move the stone. I throw the pie onto the stone with it on the upper rack. I tightened up the bracket holding the broiler element so I could have a modicum of clearance between the stone and element; still not an easy task given the clearance.
I then set the oven on bake for the first 3 minutes of cooking, then switch the oven to broiler and finish it off the with the boiler element lit up....hope this helps

Also it sounds like 5% starter at room temp of 70F for a window of 14 hours or so is workable. Also you said you used your starter when it had lots of tiny bubbles on top after deflating? Can anyone chime in if this is ideal? I usually use my starters when they are active the first time around on the way up with moderate amounts of medium sized bubbles. I'm asking b/c I want to learn.
As for the 5% starter, 70
o and 14 hours...the bulk rise was done for about 10-11 hours at 70
o or so. I then split, balled and set to rest again at room temp, around 77
o by that time. That was done for another 4-5 hours. I really don't know what I was looking for during the bulk rise but I assumed it was the same as an individual ball. I didn't want so much fermentation that it was unusable but enough to tell me the starter was working the way it should. After I balled up, I went by normal indications using a glass container.
I used the starter when I did because of the Tartine Bread book requiring a "mature starter" to make a young leaven. I may have made a mistake there but when I scooped out the starter, it was about 12 hours after feeding or so. The next time I do a leaven for the bread, I'll wait a full 24 hours after feeding. I'd like to know what's best for the pizza as well

I know you said you felt that the starter played a major role and it could have. In my experience, a starter is a starter. Meaning they give different flavors but they all seem to act relatively in a similar fashion. Just as yeast is yeast to me. I know they are all different but they all behave relatively the same. Yeast gives rise and with enough time flavor. Starters give varying amounts of rise and more flavor than commercial yeast. Sorry for the over simplification of yeast and I know this may make some folks uncomfortable to read. I would venture to guess that your results are more related to your kneading methods and fermentation process and time.
I was talking with another member today and came away thinking some similar thoughts. So much so, that I may use the exact same recipe, replacing the starter with IDY and see what happens; scientific method here we come. If I can achieve similar results with IDY, then we may have to say it was more technique and fermentation that played the major role in the crumb formation.
As you know, it takes many many variables lining up properly to get an awesome bake in the home setting. I can tell you the pizza looks pretty d@mn awesome. Especially if it had a tender crumb as well and not tough or leathery (which it doesn't look like it to me). Before too much time passes you may want to try to replicate your results without too much time passing. Once you can get that down, you may want to play around with switching out the source of yeast. See if you can do the same with ADY and IDY just for fun. You should be able to if your methods are sound and it will make you a more flexible pizza maker.
Starters are great but they aren't magical by any means. Yes they add flavor which is good, but you should be able to make an identical looking pizza with a similar crumb using any type of yeast.
Just my 2c which maybe worth about 1c. In the mean time, I'm ecstatic for you and very happy you moved forward with making the starter. Great job all around.
Cheers,
Chau
Thanks again Chau, I really appreciate the input and praise from someone like you who was walked a ton down the road others are just embarking on

I'm coming around to the idea about yeast being yeast. Comparable levels being equal, I agree it's about taste one imparts compared to another. I was soooo excited about actually have a live starter, something I was able to create and use, I probably let the exuberance of the moment get me

In the near future, I want to cultivate a starter using just flour and water as directed in the Tartine Bread book and then I have some dried Ischia that Norma sent me (thanks again Norma!!!) that needs activated and tender loving care

It'll be interesting to see what each of them bring to the table.
My hand mixing/kneading skills need a TON of work and I'm sure that along with the fermentation played a big role in the turnout. Like I mentioned, if I get froggy this weekend, I'll do a dough following the exact same procedure but substituting IDY for the starter....although not sure how I'd figure that out

At any rate, thanks again!! Here's to the next pies

Mark