Ok, well first off, I have to say that my job involves traveling, and I do much of my work in NY city and Brooklyn. I often have to spend two or three months there at a time away from my friends and family with lots of time to kill, so of course being the pizza obsessed idiot that I am, I do lots of pizza research while I am there. I can definitely say that 90% of the pizzerias in the area are baking between 400-500 degrees, with 450 being about what I would call standard. When I first got my laser thermometer I even took it with me on one trip and went around the city shooting the insides of ovens, as I am well aware that commercial oven temperature gauges are often out of calibration. Every now and then I found someone baking at 550, and I can only think of one example of a place making normal street style pizza that bakes above that and it is Difara's. Unfortunately commercial gas ovens, especially the older ones that are most popular around NY, are very poorly insulated and cost quite a bit to run when turned up all the way to 600-650. Most older commercial ovens actually max out at 550 anyhow.
I am not able to coax information out of all of the places that I have visited, but I do try, and I have been able to talk to many of the owners or pizza makers. Honestly, out of the 20 or 30 people who have been kind enough to share their recipe and methods with me EVERY SINGLE ONE OF THEM has told me that they use both oil and sugar in their dough, and they all use bromated flour. Now, realize that I am talking normal NY style pizzerias here, not the select few who have wood burning or coal ovens who are making high temperature pizzas. I am not telling you this because I think that it produces the best pizza, or that it is my favorite pizza, that its wrong, or that its right, but only so that you can realize that this is the norm in the NY area. I know that there are probably a select few places that are not using oil, or not using sugar. Every now and then I find a place where I can taste that the sugar is not in there, so I know they do exist. Personally, I do prefer a 650 degree pie to a 450 degree pie, and I agree that when you get up to those temps and higher sugar and oil are definitely not a necessity to make an amazing pizza. While I agree that any fat in a dough will tend to make it softer thanks to the ability of the dough to retain more moisture throughout the bake, I have never noticed that including it in a formulation takes away anything but a miniscule amount from the crisp on the outside of the crust. In a NY style dough we are only talking about 3% max in there, and I believe most places use less than that. I suppose that if you got up above that 3% mark an effect on crisping might get noticeable, but I have never found the need to go that high. Like you, the one type of pizza that I have no interest is deep dish. At these NY style fat levels it is still quite easy to obtain a crispy crust and a softer interior, which to me is the definition of a NY style dough.