If you keep it home, man, "testimony" works -- though if we insist on being unique, we can certainly find a better expression.
But when speaking w outsiders it's really a word that confuses more than explains our convictions. IMO, it'd be better for those of us with an inner conviction of Joseph Smith & what he did--to familiarize ourselves with different ways of expressing that conviction--lest our convictions be misunderstood or short-changed.
That was my only point, bro. Sorry if I suggested more.
mutu.