We bought our ten month old 2350 last fall. We found it, amazingly, about three miles down the street. We were getting ready to order a new 2350 and we intended to order the thermal glass. We live in a really hot part of the country and it gets colder than most realize during the winter. So, thermal glass would have been ordered if we had bought brand, spanking new and not ten months old.
With that said, we came from a Class B world to the world of Class C Phoenix Cruiser. Simply stated, it is not possible to comfortably cool a Class B when the temperature is above about 90 degrees or even less than that if you are directly in the sun. It is simply the nature of how Bs are constructed and their compact size. So, with our non thermal glass, we feel like we have died and gone to a cool heaven. I can't even imagine how much better the comfort would be with thermal glass but I am sure it is a worthy investment. Like many B owners, I made templates of the windows and cut inserts out of foil faced insulating sheet material which was stored under the mattress. On really hot days, we popped those in the windows for a miserable dark camper van in order to lower the heat a few degrees. No more! We really love our PC and one of the principle reasons we gave up the convenience of the B was HEAT. Go thermal if you have the option.
Paul