I can see at least one issue in this solution :
if you have 3 websites www1 , www3, www4, (www2 was removed) how will you do that in the new server ? You will have to add and delete the sites as in the first server in order your users e.t.c. to match
My point is that on server 1 we have domain 1 and web1_user1 and this has to match exactly to server 2.
I believe that a "simple" solution that will export Everything (www, users, emails, log e.t.c) will be a very popular feature. Can someone provide such a script ? It should backup the users from shadow file, smtp configuration, http configuration e.t.c
Also i tried to backup a website but the www folder is quite large? I stopped the file download but i can not find the back up file on my server ... Is it automatically deleted ?