Very good post. Market cap is what's relevant.
I've actually started working on figuring out the float as I type this, in regards to accounting for preferred shares. DTC shows only ~ 4.2B, so that's technically what's currently in the float, including some preferred shares (I'm working on that number). There's a certificate at TA for the remaining 800M, but those shares aren't included in the public float.
I recall in 2014 the OS was around ~350M, but the float was about ~90M -- and the float is what matters in regards to free trading shares moving pps since the remaining is held by insiders.