Excellent posts, all, especially Rod's. I've been seeking answers to the same questions concerning the amount of weight that glass shelves can support. Not even the glass company that I bought them from could provide a decent answer. My personal experience (so far) has been good with ten 37 X 12 X 3/8 inch shelves. They're supported at each end by two L-shaped metal supports. I've loaded one or two with as many as 12 HL's of varying sizes with no failures, although the average # of pieces per shelf is closer to 8. I've never used 1/4 inch glass and never even considered it - it just LOOKS too thin!!
Thanks again, Rod, for an excellent treatise!! :>)