The 705 was a great device - to the extent that I changed the battery in mine twice, and replaced a couple of the microswitches, but its memory was tiny and not backing it up is/was A Mistake. Garmin Connect solves that poblem these days, if you don't want to use Strava, RideWithGPS or one of the other third-party recording sites. Like with all computers, un-backed-up data is extremely vulnerable, and it costs nothing to do it.
But, Joe, I'm afraid that using these devices becomes much more useful if you read the manual first!