Actually, I never thought the HD was an issue, at least not for me. When I am done with a project, I just back it up to a CD. Then I have a permanent record. I cannot see changing the drives out just so I don't have to back up to CD. 20 gig is pleanty of room for most any project. Besides, every time you connect and reconnect a hard drive you do chance damaging it.
In my opinion, it is easier to backup and clean up the hard drive then it is to change it out. And if you think about it, it probably takes the same time to do so.
The real issue is the fact that I don't believe the AW16 can be expanded to a larger drive. But 20 gig is pleanty for my use. I currently have 15 songs (90 min) and I still have room for many more. As I finish them up, I cut the stero track to CD then backup the raw tracks to thier own CD and get rid of the song on the drive.
The AW16 is a great machine, it makes wonderful recordings and is easy to use. You do need to evaluate it against all others and make your own decision. The number of tracks you need, what you want to tie in and how much room you need should all be considered. For instance if you want to use it for a stage recording and you want to tie in more than 2 mics at a time through XLR then it won't do, it only has 2 XLR inputs).