They are strong enough. I have had 5 of these spitfires. Out of the 5 I have had three issues with them. All different problems. Set screws stripped on one, Y harness didnt work and one just didnt work at all. All of these were easy fixes.
All my news ones I plan to ditch the stock Y harness, retap all the set screws and clearance the wood rib just above the motor on the wing. A few of the models the wood rib hit the motor on the gear and caused it to bind and then shut off. Again all easy fixes.