I am not responsible your erroneous habits/behaviors!
( Many leave it at "He is not responsible." )
Are you saying that you only delete the images you want to download? Or that you never delete any of them? I think I'd rather doo that on my Mac, from my own HD/Folder than trusting them to a portable, easily stolen device powered by batteries that you apparently get little use from...but as they say...
"You can lead a horse to water, but that doesn't mean he can recite the Gettysburg Address!" Or something like that...
Just to throw a little more water on this issue. My camera is an early generation that does not have USB. Only the serial interface. Does not work with the MAC's I have. Have to take the card out and use a card reader. For the MOST part I love it.