For reference, the military is currently testing a haptic output with a bandwidth of something like 16 baud. (8 binary outputs, updates less than 2/sec.) While you might be able to sense things more frequently than that, it takes a great deal of attention to notice and attend to transitory signals. Really, "vibrate" or "not" in each location is a good goal; perhaps three or four levels of intensity ("twitch", "vibrate", "strong vibrate", "throb"?)