Yeah, the PH vs. Active is pretty much symantics. Testosterone is active, but can convert to DHT or estradiol, both of which are "active" too. To be honest, I have no idea "what" Max-LMG converts to. Some kind of progestin that you'd probably have to find in the Vida Text.
Halodrol's structure is 4-chloro-17a-methyl-androst-1,4-diene-3b,17b-diol. Many of the other -diols are said to be able to bind to the AR I believe because of the 17b-ol, but their activity is weaker than their 3=O (3-one) parent. Like my previous post said, this also applies to the other -diol prohormones such as 1-AD, 4-AD, etc.
As far as the stuff like M1T, maybe someone should compile a "Nostalgia" thread for the now-banned Prohormones & Designers. I'm sure there is actually already some sort of compilation like this, but I'm about to sign off, so I don't have time to look.