I got a chance to talk with Smart USA's Engineer about this question on what causes the crazing:
It is UV exposure. As of March 2012 production a new roof material has been introduced. It addresses the tendency to craze/crack as the old roof did from UV exposure.As for spare part availability this is still an open question. The main supply is going directly to production so spare part stock does not get filled as quick.It will be available in spare part supply, but I do not have an exact date at this point in time.