Its interesting how the differnet boards are holding up. We have been using a range of different epoxy and glass boards over the last 18 months in our school doing both river lessons and surf lessons and have been suprised at the differences. While in most cases the Epoxies are lighter - the Polyester Glass boards like the Laguna Bay models are still really lightweight and seem to be a lot more resistant to rail shatters.
The epoxies seem to chip and scratch a lot easier when going in and out of the SUPS van and when being hit with the paddle.
Check out this page:
http://standuppaddlesurf.com.au/content/view/14/31/ to see what i mean.
There are definitely exceptions to this rule though - the Naish boards are holding up very well and seem to be really durable.