Michael
I would question why you would want to go down this 24" track?
Pizza eating outside of the USA is nowhere as much in terms of number of shops, volume or number of times people eat pizza. I don’t think you would get enough volume to warrant doing this size and you will end up losing on the deal. Unless you have a huge volume, a huge customer base and lots of people eating lots of pizzas consistently day in day out then I think it will be a massive failure.
It also goes against any published obesity articles which consumers are being more concerned about, so you could be alienating customers by doing this size.
When I took over my shop we had 4 sizes, small (10"), large (13"), family (15") and jumbo (18"). The slowest seller by far was the Jumbo which also caused us more troubles than any other pizza. It took up more space for cooking - only 1 could fit across the 32" conveyor belt at a time; harder to handle out of the oven to the box; sales slower which cause us to throw out rolled out bases at the end of the night; extra box storage and inventory, plus you need a special size heat bag for deliveries.
In the end we decided to do away with our Jumbo 18: size.
Try working out a price for this size and then think if someone would pay that much, especially in the economic situation in Ireland at the moment. We struggled to sell the 18" Jumbo when times were good, and thew Australian wage and expendible income is much better than Ireland.
Leave the thought at what it is and concentrate on doing your other business better and you will find you will get better profits than introducing a “gimmick”.
Dave