I would like to add that from my personal experience I would not recommend the free StartSSL cert for personal use. The certs are free but revoking them costs money, so when the whole Heartbleed thing happened a lot of people got screwed. Regardless of the cert owners ability to pay for it, StartSSL made the web an arguably less secure place with that business decision and many did not pay to revoke their free cert. For a time there were even discussions of removing all the StartSSL certs from Firefox as a result [0].

[0] https://bugzilla.mozilla.org/show_bug.cgi?id=994033

I didn't have any problems using StartSSL for any of my domains, and they all have whois privacy.

Depending on the privacy providers, the protected email changes after every email it receives. This causes startSSL to deny your certificate requests