logbooks
In actual fact boys and girls, that excel spreadsheet is not legal until you print it out. then there is no problem it meets all the requirements, but has to be hard copy. And as you need to hold a log book as long as you hold your licence it is a good idea.
If you lose a logbook CASA will only credit you to your last rating, I.e maybe you have 1000 hours and your last rating was CPL you now have only 150 hours as far as they will credit you, any more and you have now falsified your log book. excel spreadsheet suddenly seems a logical.
adjust it accordingly to show when renewels are due, or how many hours left until ATPL or command on type etc...