Nice post there, which I'd view as supporting my argument in favor of calculated free testosterone. The cheap tests that most people use are lousy:
But why spend the extra money on a fancier test when you should still be testing total T and SHBG, which already give you a reliable free T estimate? Equilibrium is going to set you back $99 at Discounted Labs, versus $30 for the regular. Admittedly the extra money is going to get you a more accurate total T test too, but I'd suggest the expense isn't justified.
That's interesting about SHBG circulating as a dimer. It would be useful to know if the differences from older models are significant.