I will say that there is a significant difference in the glass in my gameroom. While the nice glass is very expensive, it also makes a big difference depending on the lighting conditions. I have Invisiglass on my WOZrr, but my SS and my ACNC have normal glass. The SS is not too bad with the reflections from the head and backglass, but the ACNC is pretty brutal with the speaker lights reflecting onto the playfield glass. I had to get one of the "bent plastic" light deflectors for now but plan to get some sort of PDI or non reflective glass for that game in the future. I would definitely upgrade if it was a factory option, but I have no problem ordering it aftermarket if I have to. The only problem with that is then I have an extra sheet of glass that I need to figure out what to do with.
I broke my original Invisiglass on my WOZ a while back and put my normal JD glass on it temporarily for some gameplay while I waited for a new sheet. HUGE difference it made as the normal glass had some bad reflections in my gameroom.