I flew yesterday, and my nosecone became totally detached. It was held on by the built-in lanyard. When I landed, there were 5 or so tears/punctures in my sail. One was as long as my hand.
So, if you ever find yourself in that situation, landing soon would cut your odds of having a torn sail. Not flying too fast would help too. As would (possibly) not having the VG on. Tighter sail might tear/puncture easier. Of course, land with appropriate speed, regardless. But don't fly fast until you get closer to the ground. The less time that nosecone-knife has to whack your sail the better!
For the full story, see: http://www.shga.com/forum/phpBB2/viewtopic.php?t=1151
Nosecone warning
Nosecone warning
Fly High; Fly Far; Fly Safe -- George