The Chrome/Firefox extension is flagged "NEW" on the download page. If these allegations are correct, it ought to be clearly labeled as insecure. I'm quite disappointed.

And BTW, I also don't like the option to upload private keys. I mean, no sane person would ever do that. It's not that hard to copy keys to multiple devices, if that's really necessary for your work flow. Me, if I used mobile devices, I'd use dedicated keys, because those things are so readily pwned.