I'm far from an expert but I've been told for reinforcing, it's necessary to do this for anything that is over 2'x3'.  For projects that are close to this size I always use the copper reinforcement between the lead/copper foil lines and it seems to add quite a bit of strength to it.

This is absolutely gorgeous!  Your choice of glass and design is exquisite.  You have something that is a showpiece.  Just love it!