You could use others materials for baffling, results may vary-too complicated to comment further on recommendations I'd make. Purpose is the huge practical aspect, and for Joe it is exactly as he states-cut down the direct sound path to the audience up front and still retain the amp's characteristics at the settings he chooses with much of the monitoring properties he needs intact and preventing unwarranted interactions from onstage. The clear acrylic is visually aesthetic as you can see the amps and mic (also good for sound engineer to see
), it is very, very tough, road worthy, much lighter than glass, and glass would break under travel unless highly tempered and the price of that makes acrylic look like a bargain. If you need 'em, really need 'em, get 'em. It's been a "family" / friends type thing from the beginning. I don't need 'em (yet
) but I can recommend them to those seeking the intent that encompasses the entirety of the needed result.
Rock ON & Keep the Faith,
Rocket
"He still doesn't charge for mistakes!

"
http://jbonamassa.com/tour-dates/"Everybody wants ta get inta the act!"
“Now, this isn’t your ordinary party crowd, here. I mean, there are professionals in here.”