Those are looking really good, John.
I like the smaller rim.
I'm curious, are you taking IR readings of the aluminum pre-bake?
While aluminum will give off relatively more of it's stored energy than steel when baking a pie, on the plus side, it's conductivity should allow it to replenish much faster, so, if, say, it takes steel 10 minutes to come back to temp, depending on the strength of your oven, you could recover in 5 minutes with aluminum. AL loses heat faster, but it also gains heat faster.
I cut my teeth on 1.25" soapstone, which had enough thermal mass to give me more back to back pizzas than I ever needed, so, for a long time, I turned the bottom element off during the bake and only turned the broiler on as needed.
For aluminum (and steel, depending on thickness and desired number of pies), in order to aid recovery as much as possible, I would never turn the oven off. In other words, when you're not broiling, use the bake setting. You obviously need to be careful not to exceed a probe temp that prevents the broiler going on (perhaps by cracking the door in a worst case scenario), but I would keep the bottom element going as much as possible.
I've sort of settled in on three variations of my pie. Give or take a few seconds, they're basically 3, 4, and 5 minute bakes. The 3 minute bake is kind of a Neo-NY slant, with plenty of contrast on the undercrust and some char. The 4 minute is my floppy NY, which is a bit more evenly browned on the undercrust (but still has some contrast), no real char and is almost always microblistered. The 5 minute is what I call my 'crispy' style, but it's only a tiny bit crispy. That's the most evenly colored/golden brown of the bunch.
The aluminum's propensity towards contrast seems to produce an undercrust in 4 minutes that looks a bit like my 3 minute pies. It sounds like you enjoyed this tremendously, as you should, but I might try branching out into more even coloration- and not just by lowering the temp and extending the bake time either. A while back, I had spoken to Marc about 'aluminizing' his formula:http://www.pizzamaking.com/forum/index.php?topic=21951.0
and I think you might benefit from experimenting along those same lines. I would try 61% hydration, and, then, after that, maybe a batch at 59%. How much oil are you using right now? If you're below 3%, I'd bump it up to 3.
When you lower the water, the pizza will brown a bit faster, so, in order to keep the 4 minute bake, I'd probably pre-heat to 525.