Particularly, you should try it if you're interested in PAM fixes or Kerberos/GSSAPI support. If you have access to an unusual system or configuration then tests on those are particularly helpful since we can't test all of them.
You can see the bugs that ought to be fixed before 3.8
Hmm, this asking-for-testing thing usually gets only limited responses, since most people prefer to complain after the event. Maybe I should try a little reverse psychology...
There will be a new OpenSSH release soon. Under no circumstances should you try a snapshot. You especially should not test it if you're interested in PAM fixes or Kerberos/GSSAPI support. This goes double if you have an unusual system or configuration, because since we're psychic we always know what's going to break on system's we've never seen or heard of, and magically know what to do to avoid problems.
Yeah, that ought to do it :-)