Q: Multiboot drive use recommendations

I am 90% following this, and will probably increase that to 99% once I am actually using that computer (am currently using my G4 with Tiger OS).   One of the problems with the clone Mavericks is I am third in line of family users of that computer so I doubt I'll be 502 (and the account was not created by me with my preferred UserID), but that can probably be resolved.

This seems to be using the same "home" (user) folder for both OSes which is clever but might I end up with problems when it comes to using applications?  There may be some applications which run under both OSes but different versions. However, preferences files are rarely distinguished outwardly application version though they are often version specific. I have done some meddling with getting multiple copies of applications to run under different identities each with their own multiple preferences files so I may get it to work but it is very finicky.  For example, I currently have two copies of VLC running, each with its own preferences file but I had to go in and edit all kinds of files inside the two copies of application and that may not always work.

I definitely appreciate your assistance. You are right about later OS versions becoming more and more restrictive. That is why I am making my next upgrade from Tiger to Snow Leopard which from what I hear was Apple's last computer-user's OS, versus newer ones which seem to be more the device-users' OSes.

I am not so concerned about the iTunes libraries (and probably the other i-libraries too) as such.  I can make multiple iTunes libraries, one for each version.  However, iTunes will be looking for a preferences file and if it is a common user folder there will be only one of those and will result in conflict.  It's that kind of thing I am mostly worried about with this common user folder solution.

No iOS gadgets, and don't worry about iCloud. I don't even have an iTunes account.  All this is ironic since I'd say 30+k of my points I have earned over in the iTunes for Mac forum.

Yes, hacked bundles. I did it for one or two applications in Tiger OS. Worked for some, not for others.  Don't want to have to depend on it to keep applications separate on this scale..

Observation: I see if I look at my clone backup of my present Tiger drive and look at my wife's account her default folders are all forbidden, and everything else is read only, but I can see inside all my user folders even though I am booted to a different OS copy.  I am presuming, along the lines of reasoning you presented, since I am using the same user name and UID the OS is allowing me access.

Idea: If I set up my account on each side with same user name and same UID (may have to edit one) I should still get similar access as I do now when I look at my clone backup (?).  If this is indeed the case then my solution may be to make symbolic links for most of my folders back to my primary use partition (the one with Snow Leopard), so when I put a file into my Mavericks "Music" it is really going to the folder in my Snow Leopard user.  The main problem with remapping the whole Home folder was going to be with applications use since I might have different versions for the different OSes and don't want the Applications folders pointing to the same place, nor do I want my user Library to be the same since the preferences files would get messed up.  For those folders which contain things which are not really OS specific I can make symbolic links to the main partition.  Media are obviously the bulkiest files but are not version specific (and for something such as iTunes I can have two libraries sharing media files, and I do not let iTunes organize my media anyway).

I am really concerned about messing up user system settings and the such.  I can easily imagine that Mavericks has added a few extra features into some compared to Snow Leopard and that setting something in Mavericks, then setting it in Snow Leopard and returning to Mavericks one might find the system is messed up.   I know iTunes is highly specific in its library files. I don't know how it is with the preferences files.  I definitely do not plan on running the newest iTunes under Snow Leopard but may continue to keep the current iTunes 12 in the Mavericks folder.  That's probably asking for trouble if I use a shared user Library folder.  Unfortunately I can't figure out how to used a shared Home but separate user Libraries, but I can see if you keep the Home folders separate and then redirect everything else to another partition with symbolic links you can do that.