Pebble: replacing tick_timer_service_subscribe with app_timer_register issues?

Question

I have a watch that updates at non standard time intervals (eg half minutes). It made sense, to me, to use app_timer_register to update the time which seems to make tick_time_service_subscribe redundant.

Should I expect any issues with the substitution.

So far, the following code seems to be working on CloudPebble.

static void timeHandler(void * data){
  find_time_to_next_update(); // updates int time_to_next_update_ms

  app_timer_register(time_to_next_update_ms, timeHandler, NULL);

  update_time(); // refreshes watch face
}