Engines are not built to be crash proof. In a crash that digs deep enough into the dirt, ALL front carb engines I have seen tore out the crankcase carb housing part. A dab of JBweld fixed it every time.
A rear carb engine will have the crank bent , twisted, or other damage.
The 35cc engine is an excellent choice, and has much mechanical reserves, and no engine has come to harm in normal use yet in the 7 years I sell them.
That is why the factory now has decided to expand it into a 40cc.