yes. use them. whether directly integrated into the horn, or into the steering assembly. the idea is that they have to be strong enough for the application, and drift will not be an issue. i use the kimbrough heavy duty one. i even cut my chassis to fit it, as it like it so much. it's way strong and never leaves center outside of crashing, which i don't do.
my car is never out of trim, ever. and yes, i smash things quite often.
the jrxs guys at our track leave with headaches all the time, because their trims are off from not running a servo saver. they can't fit one. by all means, if you can run one, then do. if the saver in your kit sucks, find a better one. or scrap the belcrank saver, and just go direct on the spline.
the idea of a saver is to purposely put a weak link in the system. one that is 100% elastic. without it you will be exposing the next weakest link. whether it's a gear, a ball stud, or a horn, it usually fails permanently.