You guys are flying them too fast .
It is that simple
The design was intended to be a slow speed tumble bug -
I did one for a magazine review using a gas engine - worked well andfound that speed of say - up to 30 mph is all that is necessary for the maneuvers .
The aileron servo mount is quite iffy -to be candid but I had no structural problems and used using JR811 servo throughout ,on 6 Volts .
The Harrier by Seagull models is a similiar example - these will come apart if speed is much above basic maneuvering speed .
These things were done to appeal to th craze of "I want it to hover".
Weight is crucial on these so integrity for fast flying was sacrificed.
I place the blame for most of these failures squarely on the customer who will not hold the speed down to the intended range.