[shimei]

I have been using SSL now for a little over two years. I remember during the transition that the site's traffic plummeted. http and https are not looked at as the same url and link juice was deluded even with a 301 redirect. All those back links to my site lost a lot of weight. They were pointing to http and not https, and when I redirected the http to https through htaccess the site lost ranking. Lastly, it took some time for Google to reindex the site and update the site's urls.

Just a heads up, be patient because it will get worse before it gets better. If you're working on SEO, save your money until after you make the transition, because building up the http address is a waste in the long run.