Thanks theOAP, charmaine and durhamlad for those good answers and insights!
I'm sure the online filing will be easy, just (as with anything else) doing it the same way I did it last year and the year before would have been easier. One advantage of online filing that I foresee is that presumably a printable receipt is generated, which should give peace of mind compared to the US mail options ... I paid for registered some years but other years just sent it off in the mail, sometimes I phoned later to see if it had been received, others not.