[gr8m8sam]

I use these lines in advancedsettings.xml

Code:

<pathsubstitution>
  <substitute>
    <from>special://profile/Thumbnails/</from>
    <to>smb://bignas1/media/xbmc/Thumbnails/</to>
  </substitute>
</pathsubstitution>

It offloads my thumbnails to my nas.

I can't speak for the addon backup. I use the backup I built into adbFire. It works fine for me.

Guys I have a question about this pathsubstitution.
I have mapped it to my smb share which have a password. I have added the path as smb source under XBMC setting but still getting usermane password error in xbmc log. So added user name and pass in the <to>smb://username:password@bignas1/media/xbmc/Thumbnails/</to> line to get it to work. Now I can see the Thumbdb structure in my smb share with all the artworks but in XBMC library only a few thumbs shows up that too incomplete poster or fanart or something else. Note: My test Library is very small around 10 movies.

Now question is - is it because of smb performance and can't expect more than that or am I missing something here in the setup. This missing thumbs actually killing the XBMC experience. Here I am being proactive for my real Library which have hundreds of movies and TVs.
What would be the best option smb,USB or native to Fire TV?

Thanks.