What is the purpose of this utility? I don't see the problem it is designed to solve, but understand there must be one!

[my star rating is meaningless, I have not used this]

Surprised that there are no recent reviews, so I wanted to say I've been happily using this for the last four years to keep offsite backups of my most important files. AASync connects and syncs/backups automatically via SFTP to a backup folder on my ISP. While I have been using this program, the developer has been responsive and has regularly improved the program.

I start a backup every night at 11:58 PM and by 7:00 AM the next day it has usually uploaded all the new files I have made in the course of the previous day. The interface looks simple, but I know that much work has gone into the code to make it work with different servers.

I do suggest you rename your Mac's files to be 'Internet friendly' names, or at least unix/linux friendly, for example, "Make Names Web Friendly" is what I use on legacy files, but mostly I try to name new files in a Web-friendly way when I create them:
http://www.apple.com/downloads/macosx/automator/makenameswebfriendly.html

I use this alongside Time Machine and SuperDuper!

If you have >100GB of files, be prepared to run this for a month to make your first backup over a typicaly DSL link. You can abort the overnight backup when you start work in the morning, then let it start again by schedule at midnight.

I bought iWow in the original offer and accidentally installed it on too many machines (that is, on machines that I no longer own or no longer use, or don't use with iTunes). I could never get the old machines to unregister themselves, so I lost the ability to use the product before I settled on my current iTunes machine.

Will the upgrade give me a new lease of life, or will I only be able to upgrade it on the machines I no longer want it on?