I stepped on a piece of carboy glass this year and it sucked but I still love my glass carboys and carboy handles. I question plastic. I know that there are different grades and what not but I like that I can see that the glass is clean and I don't have to worry that it leaches anything or something like that. When I have broken them it was always my fault. I clinked two together... it happens.. and I had one slip out of my hands... so I got carboy handles for all of them. These injuries seem like worst case scenarios. Brewing is dangerous though for sure. Heat, sharp objects, boiling liquid, wet floors, propane gas, hoses, pressurized bottles. Safety glasses seem appropriate and getting your hand underneath the carboy when you hold the carboy handle could help. I hope that no one else gets slashed or punctured including me. I'm in the glass group.
This is what concerns me more than getting cut.
http://www.npr.org/2011/03/02/134196209/study-most-plastics-leach-hormone-like-chemicals