A couple of months ago, I agreed with you. I loved my Archie's and Wiggum's more than my Sprawls and more than anything else any of my training partners owned in comparison...until I discovered ripstop material.
If you think your Forty Thieves are durable, check these out:
KORAL USA | www.koralusa.com
Keiko Sports - Black Rip Stop MMA Short
But don't get me wrong, I still think Forty Thieves are nice and I'm gonna pick up pair of Wagner's, they'll just see the beach more often than they do the mat.