But external HDDs would get really annoying. Yeah it's good for backing up stuff, but I don't want to plug in a external HDD every time I downloadna song or want to add music to my iPod. I might just do the data doubler. However I'm still paranoid about it. It just seems like a bad idea when you start trying to do things that your Mac wasn't designed for. I don't wanna hose up my laptop as soon as I buy it ya know?
i've got gobs of songs. i can't listen to them all at once, and they are all on my ipod anyhow, so i don't see any point of having all my songs in my drive. what a waste of space.
i plug in my time machine drive once a day. i move stuff that i don't need off my drive and onto the 1TB backup drives a few times a week. i definitely don't carry the hdd around all the time. why would i? if i create something new or download something, the files are backed up to sugarsync on the cloud automatically, so even if i have something awful happen between the time i download a song and move it onto the 1TB backup, i'm covered.
i guess i don't constantly move stuff to my ipod, so it's not even a concern. i can just do it when i get home, since i've got all my files on the hdd there.
obviously, having every single piece of data with you at all times would be ideal, but like i said, once you get to several terabytes you realize it's not really viable. better data management is cheaper and safer (backups everywhere).