I too have a number of add-ons I can't do without (e.g. Lazarus, Last Pass, Linkman Fox). A browser on which I can't use Lazarus, Linkman, and Last Pass is of little use to me. Add-ons were one of the features that made me switch from Opera to Firefox, though now I'm rather disenchanted with both. Fortunately, as I became more and more frustrated with Firefox, I tried Pale Moon, and I found that I could install in Pale Moon all the add-ons I had valued in Firefox. Pale Moon is now my primary browser, though I still have Firefox (36.0.1), Opera (12.17), and IE 11, in part for testing purposes. As a software enthusiast, I often can't resist trying new programs that sound appealing, but in its present form, Vivaldi doesn't sound all that interesting to me. The good news is that it's being created by some of the folks who created Opera, which was in many ways a great browser. The bad news is that Vivaldi is being created by some of the folks who created Opera, who stubbornly resisted add-ons. Of course, Opera had many features built in that were possible in other browsers only via add-ons, and perhaps the Vivaldi team will apply some of that same ingenuity to the new browser.