I'm also a fan of plastic mirrors.

Unlike glass, a cheaply made plastic mirror can warp, degrading signal output. Plastic mirrors don't have the same reflectivity as glass. Glass mirrors aren't buoyant; some plastic mirrors are, depending on construction. A glass mirror I've had for around 20 years got a dime-sized spot of corrosion at one corner, between glass layers, caused by moisture. Haven't with any of my plastics (but not saying couldn't happen under right conditions).

According to Rescue Reflectors, Inc., who's tested various makers' plastic mirror signal strength against same-size glass mirrors, plastics signal strength ranges from 14% to 85% of glass (majority in 14-67% range).

But, as cedfire so aptly put it, "Any signal mirror is better...."

Dan