Threads like this make me glad I never invested in any glass carboys. Had an incident when I used to work in a lab once; I was using a nice, thick, heavy, 4-L pyrex rotovap flask, swirling solvent in it to get material out of the flask, and it slipped out of my hand, fell maybe 4 inches onto one of those black chemical-resistant countertops, and it shattered into a few dozen various-sized shards. This was high-quality borosilicate glass. There might have been a tiny crack present, or an invisible imperfection, but I inspected the glassware each day before use, so there was definitely not a large crack that was steadily growing over time. Luckily the flask was moving away from my arms, so I avoided any cuts from the accident. I can't imagine trying to manipulate 5-gallon glass carboys, slick with water, of variable or questionable quality. Just way too hazardous for the advantages of using glass to overcome.