Sub plexiglass probably wont flex as much but we are talking 1" thick or more. The cost of it is not worth the benefit. Unless all you want is looks. If you just want the looks of it then just put in a plexiglass window. Dont make the whole thing out of plexiglass.
Thats like people wanting to do carbon fiber instead of fiberglass enclosures. The cost benefit ratio is really not that great.
The only advantage a plexiglass enclosure has is that there is no air leaks.... Its air tight... Look really nice also... Doesnt need to be that thick... Here is a good site... http://www.gatelyaudio.com/
I thaught you had the hookup with audio equipment too. So i was like "if everyone had the hook up like you (with audio equipment), then wed all have loud @ss systems". My bad, i wasnt more specific. but thats what i meant. I dont know if i would go with an entire plexiglass box, maybe just the face with some neons or a window. Sorry dude
My bad man... I would recommend the wood, you can have someone sand it down and paint it, where it looks like fiberglass, or you can fiberglass it, you can carpet it, or you CAN put some plexiglass like, a window or sumthin.... you can do alot, far more than with the glass.