I think any layman can understand the impact of a thought of card arriving at a thought of number without the magician ever touching he cards. Presented properly, with emphasis on the right attributes, it'll astound an audience as well as any other version of ACAAN, and it's cleaner.
I'm sure they can understand how impossible of a situation it is, but wouldn't it be better to simply have someone name a card and then show the card on top of the pack? It's more direct, nothing to clutter the effect. In my mind, unless you've broken down the odds of it happening, which is usually a pretty boring thing to listen to the magi ramble on about numbers, it doesn't seem any more unlikely. That brings me to another point, it's an unlikely occurrence, not magic. Paul Vigil is a good friend and mentor of mine and he has a line that I love and caused me to reexamine a lot of my magic. Paul said "Magic isn't a 1 in a million. Magic is a 1 in a mother******* can't." Maybe I'm spoiled or jaded, and this is coming from someone that's played with the CAAN plot for a while, but it just never struck me as a great plot. I'd rather just produce a named card from my pocket, which is one of the strongest, least cluttered effects you can shoot for.