In two years the only things i have broken is a belt, a driveshaft in its first lap and drive shaft blades on the lp. Not a problem on the cx. My mate has only ever broken a rear shock tower and a rear wishbone, both from very high speeds, and altitude
There is another CX and Mi4 at our local track and i have seen the mi4 brake a spool cup after the blade come off but thats it.
Never seen a weak area in the mi4's. Its not indestructible like any of them but always different things on different cars.