The jury is split. Is there any harm if one leaves the jib furled when storing the boat. Assuming one uses the "snorkel" cover to protect from UV, is there any harm?

If it's a play jib I don't see anything wrong with it. If It's your only good jib I wouldn't do it. The snorkels I've seen that were in good shape will hold moisture ( if they help keep water out, they will help keep water in). The ones I've seen in poor shape will breath but they will let the light through, degrading the sail. A friend that just cruises his boat had a heavy sail cover type material added to the leech and foot of his jib so when he furls the only thing showing is that cover material. This is what monohullers have done for some time to protect the genny. This leads me to my question to you, big boats do it to make sail handling easier (big sail,few people) Whats the problem with taking that little jib down when your done?

OK....you got me! I was just being lazy and trying to reduce rigging time from trailer to water. Your points are well taken, however...

With exception from possible damage from the elements...does it damage the shape of the jib? The jib in question is from an I-20

I would say yes, even without weather damage. I have a RF on my I20 and notice that with just leaving it furled overnight, the jib shape is distorted in the morning. I imagine that if left furled for a week or more, this distortion may not work its way out.

What Mike says, and I go out and stay out for several days at a time and I admit I don't take the jib down. I will ease the luff tension off and unroll the jib and then roll it as loose as possible. I would find a older jib or have a heavy duty one made and leave it up and keep your good one for racing

Have Fun
Mike