I have the feature. but never use it. If it is raining hard enough to have the wiper on.. I turn it on. Otherwise I leave them off.
I too use Rain X and find I hardly ever really need the wipers unless it is pouring. (or to clean off the screen with a wash)
I hate wipers doing there own thing, and have never had a problem with the auto wipers.
I just control the wipers myself.