Is there evidence that this is indeed the case? I've seen much FUD but no actual data that shows that a properly updated site (301 redirects, HSTS, robots.txt) is penalized.
It's FUD. Google has already confirmed that switching to HTTPS will not hurt your site.
>Do I lose "link juice" from the redirects?
>No, for 301 or 302 redirects from HTTP to HTTPS no PageRank is lost.