There are plenty of ways to fix that add-on compatibility problem. After all, being a Nightly UX user and all, I’ve found that almost all of them work, and the only one that doesn’t work, isn’t really important *Which is Greasefire, Greasemonkey works perfectly*, nearly all work perfectly. An easy way around the so-called “Incompatibility” problem is similar to this

http://lifehacker.com/355973/make-your-extensions-work-with-the-firefox-35

Although, it’s a bit difference, you just add a new boolean value called

extensions.checkCompatibility.(Version Number) and set it to false. There’s not much to it, even to a newbie, there are plenty of guides that will help you through it. Even if you’re afraid to touch about:config, you can install both Add-on Compatibility Reporter, which, I think, comes default now with Firefox, and Nightly Testing Tools.