Classic Theme Restorer was built by an developer who didn't like Australis. He/she needs to keep it updated for future versions. If the add-on quits working on any future version (e.g. Firefox 32) , Mozilla (nor us) aren't liable or responsible for picking up the slack. Developers are encouraged to keep their add-ons updated for the new Firefox every 6 weeks. If not, then you're outta luck and just have to wait or bother the developer for an update.

My personal opinion as a user and not a Moderator, I think CTR will fade sometime as Mozilla isn't likely to reverse the UI changes unless they see a HUGE drop of users and because more and more add-ons will be made for the Australis interface and will clash with the CTR add-on. So just be aware that CTR might not be available or working in future versions of Firefox

I see no problem with updating to Firefox 30 and using CTR. I've tested on CTR on Firefox 30 and the Firefox 32 Nightly build and everything works fine. No errors or misplaced icons

The CTR extension is not going to fade anytime soon with the vast amount of work the author has put into it to make it work on the versions on Release, Beta, Aurora and Nightly channels starting when Australis first showed up in development.

http://forums.mozillazine.org/viewtopic.php?f=48&t=2827985 http://forums.mozillazine.org/viewtopic.php?f=48&t=2773133

Note that the current Firefox releases store the toolbar customization in the browser.uiCustomization.state pref.

I used to have Firefox set to update automatically, but when 29 came with that awful Australis look (with no 'off' button) I installed CTR and after about an hour, I had things more or less straight again. Learning my lesson, I switched the auto-update off.

If I update to 31, will CTR still be there, and work, without my having to waste time re-installing and re-configuring it?

Yes, as other support contributors have stated CTR will more than likely be around for a long time.

You can take a look at the number of different version that have come out to assure yourself that the developer has a lot of time invested in that add-on. https://addons.mozilla.org/en-US/firefox/addon/classicthemerestorer/versions/

I started this thread and I have updated twice from Firefox 29.0.1 to 30.0 and now Firefox 31.0 I had no issues with errors or misplaced icons. If there was anything moved around, it only took a couple minutes to get things back to the way they were before the update.

What is a bigger issue is when your on a web page and you click the back button to go back to a Google search. FF ether jumps back twice or produces a white/blank page. (Frustrating!) I'm constantly reloading the Google page. It kind of takes the browsing out of the browser.

'Classic Theme Restorer' does not have anything to do with the white/blank page issue.