Classics aside, every magician should change every trick to suite their own style of performance. I agree something can get lost if you are not careful yet every effect out there today is built by principles of tricks that came before it. Doing the torn corner with an index playing cards works a treat on large and small stage, however doing it with jumbos and a watermelon to me just screams comedic value that doing it with an orange would not give. If I was a beating man, I would say at the next convention contest someone will be doing this after reading this thread. So for me I say go for it, get your laughs out of it and make it yours.
If you do decide to do this, I would suggest you open a small fruit first, and find nothing in it. Then realize you were using jumbo cards then pull out the watermelon for the final reveal. Everything leading up to the card and the corner matching are just bits of business for comedic value, when you go to show the match that is where the real magic happens. I have been doing the card to imposable location with a torn corner for many years, the key is to recap the impossibility of it being their card and proving it with a perfect match.
Good Luck
Floyd

I'm glad this thread is generating lots of discussion. It's just what I wanted.
Thank you all for all of your ideas, thoughts, and critiques on the subject. I'm learning everyday not only from books but you guys as well. I appreciate all of you taking time to help me.

Chris, makeup, Bill- thank you for the helpful thoughts.

Michael- I understand exactly what you mean. I have a comedic routine, so I'm just piecing together what fits. Thanks for laying down your knowledge on me.

Floyd- I love your idea. Thank you for your advice.


Back to the drawing board.

I have done the card in orange for large groups of 100 to 200 people, and it has always played well. I always use a black spot card instead of a red one, as there is better visual contrast. For that large of a group, I don't use court cards, as they all look alike from that distance. The presentation that I use is that I am going to teach them the magician's and gambler's technique of marked cards (said with tongue planted firmly in cheek). I tell them they have to look closely as the marks are very hard to see as I am tearing off the pieces. The torn pieces go into a "card box." Before I hand the card box to the assistant, I tell them I am going to reach in and get them a receipt (the torn corner from the card in the orange). I have them open the box to show that nothing is inside. I then cut open the orange and take out the "restored" card, minus the torn corner which they have in their hand, which matches perfectly.

Bob Phillips