I'd go for the die-box too
Run Rabbit Run is great with a younger audience - in fact it plays very well to the youngest audience you would probably ever get a booking for -but I have found that when the audience is above 9yrs it just doesn't play as well as the die-box.
In my opinion the die box works well for any audience 6+
If you are looking to fool ALL your audience badly stick to the die box. If you are working a party with younger kids who you want to scream while the parents think - "that's clever" with a kicker at the end then maybe the investment into Run Rabbit Run for you is well worth it.
The die box i use is the MAK JTL version available from here
http://www.emagictricks.co.uk/product_info.php?products_id=3453 a great quality die box and a decent price. The run rabbit run i have cost me $35 dollars from ebay new. Not the best quality - but for the times i have used i have def. got my moneys worth.