Well, not sure about cancelling H1, but you could be asked at PoE on your current role, etc. There have been many who have traveled on F1 OPT and have come back...also, there are few who have got issues at PoE...Unless you really need to travel, I would not travel during this time as your COS will become invalid and you need to do COS again or exit and re-enter to get your H1B status.