Hi Matthew,
I think the main contributor to cracking (there have been other incidences of this reported in this thread) is that the gear supplied with the airframe is very rigid, they don't flex at all which means in a harsh landing the impact is transferred to the weakest point of the airframe which is where the CF mat on the inside of the fuze terminates.
I replaced the supplied gear with a set of Bolly gear which is heaps more flexible. I have had 160+ flights in my Integral and all is well (other than damage casue by an idiot pilot - me!).
Repace the gear with something with more spring (unfortunately you will find Bolly gear hard to get now) and the load on the airframe will be greatly reduced in landings.
All the best, Simon