In reply to Spanish:
Yes, I seem to remember 5 years is the figure that usually quoted in the labels you get on slings etc. (assuming little/no use). No doubt that's a fairly cautious figure but this is safety kit for you and your kids we're talking here so i'd personally get uncomfortable leaving it more than that.
The only other point I can think of is damp when it comes to lofts and plastic bags - I've pulled some fairly nasty-smelling things out of plastic bags in my loft before!
Steve