From what I've seen, the stock plastics are fairly thin (& brittle) so are possibly lighter than a good serviceable set of glass equivalents. Technically you are taking the same glass fibre and coating it with aluminium and it therefore would be heavier. By bugger all though.
If you crashed with a cosmetic top layer of Texalium then it would be very hard to repair back to a 'good as new' look. Glass would be much easier to repair than the OEM plastics imo which is how I would possibly gauge a measure of strength. Glass would have a better 'crashability' than the plastics.