My experience with Firefox Nightly for ~1 year below. Ironically, the nightly sounds more consistently stable than the current release build then!:
* Never had this tabs problem
* I can see about:config
* Bookmarks are fine and there's no mention of Pocket. Bookmarks show up ON the homepage, but yeah not being able to set a bookmark / any URL AS a homepage is a bit of an annoying feature lack
* URL completion works as I expect it to, although it does bug me how it strips the protocol from the URL so I have to manually type in `http://` for plaintext sites even when I've visited them before; depending on who you ask that is considered a "security feature" but kinda annoying. Other than that, I start typing in a URL and it shows me suggestions from my history followed by option to use my preferred search engine to search it.
All in all, I've not really felt FF (even nightly) be particularly different or unstable to using chrome.
Second comment I've made in this thread where I'm replying (ever so helpfully) "Huh, but it works for me" so I'll stop now :-). I promise the Mozilla Foundation aren't bribing nor blackmailing me.