I wouldn't worry about pyrex glass breaking any time soon. My glass dildo has been through HELL, I'm talking major abuse.
Here's what EF says about Pyrex:
A glass is an inorganic non metallic material that does not have a crystalline structure. Such materials are said to be amorphous and are virtually solid liquids cooled at such a rate that crystals have not been able to form. Pyrex, a brand name for borosilicate glass, is made by adding boron into the mixture of sand, soda and ground lime.
Pyrex is a hard material with a high chemical resistance and mechanical strength. The boron in Pyrex reduces any stress caused to the material due to temperature changes. It is less dense than ordinary glass, making it much more resistant to shattering and breaking as well, if it were to break it would not shatter or splinter into tiny pieces but instead it would snap or break in large pieces. It retains temperature extremely well and requires only a little lube for a super-slippery effect.
Hygiene And Maintenance:
Glass is extremely smooth and nonporous. Easy to clean, with soap/water or sex toy cleaner. Use condoms if sharing.
So if you drop that baby and on the chance it breaks it's gonna break in big pieces not shatter into little pieces.