I am in the same situation you are, frogman. I'm deciding between glass and acrylic for my upcoming 190 gallon. Right now, I'm leaning back towards acrylic. Glass is a lot more scratch resistent and deal with the heat of MH better, but acrylic is clearer, lighter, cheaper, and more easily customizable. I do worry about all the coralline that is going to start encrusting acrylic (does more so then on glass, and you have to be a lot more careful to remove). It's really the scratch factor that is concerning me. My acrylic will be "overbuilt," just in case.