As Perfect Forward Secrecy is as popular as never (a positive sideffect of heartbleed) I think it would make a lot of sense to also display the Key Exchange parameters more explicitely as part of the SSL Server Test.
The secure Key Exchange is a core component of Perfect Forward Secrecy and it would imho be justified to give it a bit more attention.
If technically possible detection of standard DH params of Apache, nginx and others would be helpful as it should actually result in a downgrade of the security rating. I would bet that the standard configuration is surprisingly common and definitely a risk according to the openssl documentation:
"The risk in reusing DH parameters is that an attacker mayspecialize on a very often used DH group. Applications should thereforegenerate their own DH parameters during the installation process using theopenssl dhparam(1) application." (https://www.openssl.org/docs/ssl/SSL_CTX_set_tmp_dh_callback.html)