Barry, you seem pretty happy with your current results. Steel will take you into a puffier/moister/less crispy realm. It's not often that I say this, but if you prefer a drier crunchier crust, steel might not be the answer for you.
I took a look at a photo of Marcos pizza, and, while I couldn't see the crust in the shot, it wasn't giving off that much of a NY vibe. It actually bears a slight resemblance to a much more heavily topped American style pie. The fact that you live close to New Haven but haven't spoken much about the NH places leads me to further believe that your taste might run on the American side, since I consider NH and NY to be very similar. Steel plate would take you into a more NH territory than you are now. Am I correct in my assumption that you're not thrilled with Pepe's?
Everyone on this planet should have a 4 minute pizza at least once, but, in your case, if it isn't broke, it might not be worth fixing it.
Thanks for your reply, Scott. Your description of puffier/moister/less crispy helps me start to understand what steel can do, but I guess I won't know until I try it. I think the issue might be that my taste in crusts runs more to that, but my wife and son prefer a more crispy crust. This dough made with the starter was moister and I definitely preferred it. I'm assuming that having a steel plate made won't be that expensive, so having that and the cordierite kiln shelf might be good until I decide which style we prefer (pizzamaker gets the final vote... I hope).
I just took a look at the photo of the pizza on the Marco web site, and I see what you mean. I've never seen one with that much cheese come out of their oven. My arteries are clogging just looking at it. Even though the owner used to work at Pepe's, Tom went with deck ovens when he opened Marco. So you're right... it's not NH style pizza. I think it's closer to my experience with NY style (nice puffy crust, tapers to thin, foldable, with a good droop to it, but maybe a little more crisp... don't know because I haven't eaten that much NY pizza in NY), but I don't have your level of experience with it.
You are correct in your assumption that I'm not thrilled with Pepe's for a bunch of reasons. I don't like the waiting in line for long periods, I find their service to border on obnoxious at times, and their pies to be really inconsistent. Sometimes the char is a thing of beauty; other times it looks like someone took a blowtorch to the crust, and it is cinders, masking all other flavors on the pie. I like Sally's better.
I was in NYC in May, and we went on a walking pizza tour (gee, I hope you're not that Scott

... even though he wasn't our guide). Lombardi... super disappointed. John's was good. The third was so unmemorable that, well, I can't remember its name. Gotta get back and do a real tour with some pros

I wouldn't say that I'm that happy with my current results, especially when I see what others on this site are creating. I'm at the very beginning of my pizza journey, and enjoying it a lot. I always want to learn and improve, especially when it comes to getting a more flavorful crust.
Barry