To avoid any misunderstanding...
PDI is coated 3 times (diving process), then burnt into the glass (merging process).
As far as I'm informed Invisiglass is coated using a sputtering process.
This might be the main reason why the surface properties from both (PDI and Invisiglass)
Maybe Jack can chime in and clarify.
Quoted from pinball_customs:
I've spoken to Roman directly, the process of making his glass is very expensive so there's very little wiggle room for price adjustments. Pinball is a very tiny part of his market, displays and museums are his primary market
True x3, btw. my primary market is the IT industry, Telecomms and Consulting.