I just went to the cupboard, got out the bag of Hen mushrooms I dried 9/2010, and took a bite. Yep, still crisp!
You will love your dehydrator and mando! Since stuff dries at such a low temp, there is no risk of burning. I like my tomatoes and apple slices on the leathery side, but if you want stuff crisp there is no harm in leaving it in longer than the recommended time. My dehydrated watermelon is crisp, something I would not have believed.
You may want to consider a kevlar glove for use of the mando. Saves your fingers and much more manageable than the guide.
Have fun! I'm excited for you!
She who dies with the most toys, wins.