I have only used savox 1258/1268 in my off rd cars, mainly the 1258 and not had any issues. never stripped a gear or anything. in a multitude of different buggies. none with servo savers fitted.
The new xray xb4 i have has a saver fitted from factory, but all previous buggies never had them and in the last 20 months or so not one issue.
I would like to say i have had some incrdible crashes when i returned to racing 20 months ago and i am surprised i didnt break a servo.
For me the savox is as strong as they come, a little hungry with power draw but defo strong.
The 1251 has had issues i have seen, maybe the low profile part of it makes it weaker?
Maybe you have just been unlucky......