Thank you for your feedback.
I have not yet tested personnaly but I had performed a review of the code that seems effectivelly contain now the fix to process correctly the sharing and the symbolic links.
I confirm that JoomlaPack 2.3 seems to be OK now but I have not yet use it.
I have just reviewed the code without execution.

My feedbak about JoomlaPack & JMS :

Configuration :
- Joomla 1.5.14
- JMS : Version 1.2.10 (Latest available: 1.2.10) / Patches definition Version 1.2.13 (Latest available: 1.2.13)
- JoomlaPack : 2.3.3 (2009-09-09)

JMS Architecture :
- A Master
- A Slave (based on the master) installed in the /multisites/slave_id folder (who contains symbolic links

My first tries to backup my JMS sites with Joomlapack failed, Joomlapack generated a unlimited size JPA (Joomlapack archive format) archive (a 1 Go file vs 30 Mo file). The backup generated a error because the file size arrived at the limit of my storage space.

I excluded my /multisites/slave_id/multisites folder but backup failed again for the sames reasons.

After look at the Joomlapack advanced configuration I see a option about "Dereference symbolic links" that i set to no... and It works. My backup had a normal size.

My backuped site was host on "xxx.ovh.net/~multi". When i try to resintall my backup site on "xxx.ovh.net/~test". My master frontend (xxx.ovh.net/~test) was ok but not My Slave frontend (xxx.ovh.net/~test/multisites/slave_id) who generate fopen fread fclose filesize errors.
About my master backend when i'm going to JMS administration there is fopen et JConfig errors so i can't access to JMS administration.

See my screenshots in the attached zip file ("JMS-JoomlaPack Reinstall Errors.zip")

The attached file

As I have already written in the forum, I do not trust the accuracy of Joomla Pack.
I thought it had solved the symbolic link problem but this does not seems to be the case with your explaination.

I suppose that the "dereference symbolic link" impact the backup and does not restore it correctly.

Personnally, I am using a SSH terminal and directly use the "tar -cvf" command for the backup and "tar -xvf" command for the restore.

Something that you must take care when you restore slave site is the "index.php" files that directly call a hardcoded path where is located the master website.
If you don't restore in exactly the same directory structure, this maybe the origin of the problem.

Based on your zip, I think you restore something in a directory test and try to access a file in /home/multi" where you have a permission denied.

Starting from there, all the file dependency can not be resolved as you have a permission denied.

I understand now why it's doesn't work in the other folder (/home/test vs /home/multi). The integration of JMS with JoomlaPack do not seem a easy thing....
I will have to find another solution to make backup of my JMS Site (files+db).