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Any thoughts on this from the developer? The lack of Tabs Outliner is literally the only thing keeping me from switching to Firefox now.

Just wanted to tell that Google Drive Backup feature has saved my butt today. Thank you, friend! :-)

There is just one step left to integrate the tabs from the other computers into the main TO window, but it's really a minor usability issue now, as these tabs are, in fact, already accessible via Backup tab in options.

And there is a detailed guide here (not everything is applicable though):
http://www.incomediary.com/ultimate-guide-how-to-m...
A few quick tips from Kickstarters. You can't actually start a Kickstarter campaign for a browser plugin (you probably can on indiegogo), but worth reading anyway: the principles are the same.
http://www.entrepreneur.com/article/229782
http://www.entrepreneur.com/article/226731
By "the amount of donations is not unsurprising" I meant "not surprising" of course.
Well, the amount of donations is not unsurprising. Fundraising always requires a certain amount of effort — you shouldn't expect the constant flow of donations if you don't actively promote it with fundraising campaigns. Refer to Wikipedia as successful donation-based enterprise — they've spent about $4 million out of their $35 million budget on fundraising activities in the 2012-2013 fiscal year — more that 10% of all income goes into promotions to ensure future donations.
Anyway, is there a way to accelerate the development of sync features? I personally would donate up to $150 to this cause. If you push an update for your extension that will show a banner on top of the extension window (of course, closable and with an option not to show it anymore) pointing to the site where a user could pledge a donation for that specific feature — as many as 100 users out of all your user base could donate enough for you not to work for a couple of months to finish all the much-requested features.
Any news on this feature's progress?