The ability can miss. Every one has a base defense of 5% with sorcs having a base of 10% and snipers with 20 while in cover. That means with 101% force accuracy you have a 4% chance to miss on every dot tick on your standard target.
Back on topic though, this needs to be tested. Soonerjbd you have a sorc and sage correct? Can you test both abilities in a duel and see which is there is any targeting difference?
Defense doesn't work on force and tech attacks, only resist do, and resist chance is very rare and never goes above 2% (except for a few seconds when an assassin uses force shroud or the shadow equivalent).