You should be able to do a reasonably low cost poke or scan right around the time where you could branch off in several different ways. IE right when your TL Factory is finishing, poke or scan to see composition. MMM = Siege or BFH/Banshee, 1/1/1 = Thor rush. If you get surprised by a wave of stimmed infantry, isn't that kind of your own fault?
Just love Medivac + Thor combo, like an XXXL version of Blink. Drop right on sieged tanks and pick up to the high ground to get a quick repair and swap it out for another Thor, rinse/repeat. Also Thorships can swoop in, take out buildings/forces near the edge of a base very quickly and take a fair amount of punishment before picking up and retreating. Like an Immortal drop with better survivability.
I personally love Air Terran, but it's biggest bugbear is surviving the early game. I'm wondering if a better player than I could use the defensibility of a Thor FE (just a couple Thors) to both get a 2 base infrastructure to support a very quick build-up into a strong Air force. Also, the opening would hopefully force exactly the wrong response from the opponent, as units that counter Thors well are particularly susceptible to Air + BFH. I was thinking of it like the Synystyr 4-port build vs. Protoss where early Thor + Bio pushes Toss to Zealot/Immortal/Collossi and leaves them with few answers to 4 Starport's worth of constant Banshee.
Not to mention you now have a great supplement to your airforce, as anyone who has tried to fight pure Viking vs. Viking/Thor can attest, and the very high number of shots would make opposing PDDs last about 1 second. Fast +1 Vehicle Weapons will be standard after patch 1.4 if you want BFH's to have the same power they used to have and it allows Thors to 2-shot Marauders, So that's not a waste. And you could quickly snipe off Turrets/addons/Rax/etc.... Dang, this is sounding better and better the more I consider it.
Anyway, last part is pure theorycraft, but you never know till you put it out there.