Cos,
HHT is controversial, so if we get some excited posts - you'll understand. Some do, some don't - ya picks yer poison.

Most would be quick to say (I agree) that the test has to be calibrated to *your* hair or some known constant.

As to degrees or variations - this might be helpful. Mods - if this is frowned upon - just delete.
http://coticule.be/hanging-hair-test.html

I noticed that this was in the beginner's forum - FWIW, I couldn't get any edge to pass HHT when I started - including one shapton 30k edge from Glen. Let's say it wasn't the blade's fault