I think it all has to do with how the body is molded and how many sharp corners are in the shape of the body . Seems too me bodies that have sharp angles in them crack at those points easier ?
I have a JC Raptor on my Hyper10 that is over a year old and has many races/practice sessions on it and its only cracked by the front fenders where most bodies crack anyways .
BTW I use shoe goo and drywall tape as well , makes ANY body last much longer than without . There are other things you can do as well to help save your bodies from cracking like making a large plastic washer to help keep the holes around the body mounts from cracking , I use the plastic from coffee cans but detergent bottles are a good source of scrap plastic .
Here is a pic of my Hyper with the plastic coffee can body savers , it adds support too the body around the mounting holes and helps keep it from cracking .
