On all the SEO podcasts and another SEO forum the general consensus was it's not worth it unless your site wold benefit from encryption. HTTPS also slows sites down a tiny bit, which is likely a factor in Google's algorithm. I think any site that takes private info like credit cards, SSN, or even logging in and logging out if there is potentially really personal data stored in the site, they should have HTTPS, but not the cheapest certificate you can find!! Nice that it should give a little boost to domain authority though.
Also HTTPS has its issues. It's very easy to hack in many forms. (I learned a man in the middle trick in school as proof of concept.) Also a lot of people don't have a working CMOS battery so their date and time goes off by years causing certificate errors. Not to mention other reasons people sometimes get certificate errors even though the site paid the bill and its working for everyone else.
My guess and from the SEO experts I've heard from, it's probably not going to give much of a boost. Highly recommend if the site has sensitive data though because then you kill two birds with one stone, but going out and buying a dedicated IP, then buying the expensive SSL cert, it's like around $80 to $200. I would love to see some tests though as if it really does help a lot then I'd invest. But keep in mind it does slow the site down a tiny bit.
Personally I think one of the best things to do right now (after proper keyword research and planning) is building killer content. Also, getting Google Plus reviews and +1's has been getting my attention. So much so a VERY famous SEO podcast asks for it every episode and raves about how much it helps, backed by tests and by ex Google employees. NEVER do fake reviews. Personally I think it's wrong to even ask for a good review, I just tell them it helps out a ton and to please be totally honest. I also ask if they can +1 me and add me to their circle.
SEO is all about content especially right now. Build an excellent site with great content that engages the user and you will get natural links and surely better rankings. I like to pretend Google Staff is always looking over my shoulder and actually read their TOS and try to remember and understand everything. lol
Everyone focuses on unnatural link building which is such a bad idea or at very least a waste of time and money. That's because (my theory) if you are buying links but nobody clicks on them, Google sees the link as pretty well worthless. I've noticed Google not caring as much about the "no follow" tag? Anyways people seem to forget that links should come naturally by building great content. On sites that use No-Follow as long as you think people will use the link the worst case scenario is you get more traffic.
It's like people forgot that incoming links are for getting traffic to the site not solely for ranking which most people don't do correctly the black hat way anyways. Just my two cents. I'm no expert by any means just obsessed with internet marketing for some reason.
414,999 (They are currently roughly the 414,999 most popular site in the world. They were a lot better and down 382,500 ranks! (Google, Facebook, and Amazon for example are probably in the top 3)
160,626 Here is 