Depends on what temp you like to launch at for your best results. I'd personally welcome the extra 35.
As far as the steel, I hink pricewise, it's mostly a wash between Baking Steel and Dough Joe. Dough Joe charges shipping, Baking Steel doesn't. Don't know about the pricing at sizes beyond the signature 1/4" I do know that Andris provides great support at Baking Steel and is a pizza enthusiast himself.
My experience is that I started with the Baking Steel 1/4 and it improved my pies greatly over my stone (which broke anyway) I thought the pies baked very well on it and I still do. But based on board discussion I wondered if I was missing something by not having a 1/2 steel. Two things held me back from getting the Baking Steel 1/2: the weight and the over hundred dollar price. Couldn't justify it. And as far as the weight, some board members, including Mary Ann, mbrulato (sorry if I'm missing mentioning others) came up with the idea of having two smaller pieces of 1/2 steel that when placed together form a good-sized baking surface. Still heavy, but far more manageable.
I too, wasn't excited about vinegar soaks, scrubbing mill scale, steel wool, sandpaper, and all the attendant mess and pain-in-butt. However a local steel fabricator was happy to make both pieces to exact size, finish the edges and clean them up..not so they were ready to use, but enough that they weren't a nasty mess..for 40 bucks. Deal. It did take some vinegar and some scrubbing and some detergent and some steel wool and a lot of paper towels and then some seasoning...all well detailed on the board by Scott123, I believe it was. Very helpful and easy to follow. If you've cleaned the stickers off a Blackstone, prepping the steel is a piece of cake.
Now I'll say that I'd be hard-pressed to tell you the difference, or see or taste the difference in the finished pies between a 1/4 and a 1/2. But what is a dramatic difference is the recovery time between pies. usual preheat/5 min broil warm-up/bake/finish with broiler protocol, the 1/4 took 11 minutes until it was ready for the second pie. The 1/2 seemed like it was ready within a minute or two. Not quite sure what happens with subsequent pies but I'd think some advantage remains.
The 1/2 steels are heavy enough that I keep them on a basement shelf between pizza bakes, but I usually leave the 1/4 in the oven unless I'm baking or roasting something splattery
Really, you'll make great pizzas either way..just a bit quicker with 1/2 inch.