Good work Himself,
I'll admit I don't understand a lot of this root.root or user.user or any of the su.anything, but probably 'cos I've never used linux or unix.
Only one question, what are the advantages of your image over sirdoms 0.2.1, either now or in the future.
Again, good work.
There are no advantages, none, you are losing out on functionality. It might be handy in emergency situations, or for folks experimenting with the linux side of things. I like Aldiko so I have it included (1.2.10), so that's different. I might get something working with a read write filesystem, and different sized partitions, dunno. If I do then it is still on the geeky/linux side of the equation, hacking and such. General user features, not so much. It's basically stock Archos with root and some of the bundled apps gone, and there are some geeky add ons. SirDom will probably do another update and make it totally obsolete. :)
Quick run down on unix/linux and file attributes as I understand them, it's been a while:
All files in the linux filesystem have ownership and permission attributes, extra information stored along with the file, along with last modified date/time, last accessed date/time that you may be familiar with in Windows, etc. Who owns the file determines who can access it, and if it's an executable or script, the ownership controls what other files can be accessed by it. One security issue with linux is running something that is owned by root, whatever code is run can pretty much do anything, and whatever code is called by that program also runs as root, any files created inherit the program's permissions and ownership unless told not to.
Access permissions are read, write and execute, where execute can mean different things, for directories it means you can open them. These access modes are broken down into 3 sections, one for users, one for groups, and other. This is more about multi-user environments, where you have groups set up in /etc/group, faculty, students, etc. So if you have foo.rc, owned by bob of group faculty, and it's group permissions are rwx, you can edit the file and execute it. None of this really matters for Android since there is no /etc/users or /etc/group.
In the official Archos firmware, just about everything is owned by root with full user-group-other permissions, which is ok, since the file system is read only and ro.secure=1, which means you are not running as root and can't enable it, usually. When you change that, every program with ownership set to be root is running with elevated permissions, so you might has Settings saving a file that can only be accessed by another program with the same elevated permissions. So, you calibrate your screen only to find that you have to calibrate it again next boot because the file can't be read because it's owned by a user/group with higher clearance than the program running.
Bottom line, the permissions that might work when there is no root access allowed change once you enable root. It's like turning on your security system, before you could open and close your front door at will, now if you don't enter a code you get the cops showing up. :)
Hope that helps..