Ehhhhhhhhh. I mean the 2 base muta all in is at what, 10 minutes? As long as you're getting your factory two tech labs after your two armory, and you DON'T scout spire, you can get two seige tanks instead of 2 thors.
With Flash mech build as an expample. Am I really losing that much by cutting an early banshee (probably the 2nd) to use my 4 hellions in a drop with a medivac instead? That will absolutely hit pre mutas, and if an all in is coming I'll still have Seige tank and maybe 2 banshee's out before some 2 base (or 3rd hatch for production) ling bane or roach ling/bane all in right?
I think I'd be ok provided I scout it (or at least the push out) and lift to my main, or pull the SCVs preemptively.
I normally use variations of, or strictly:
http://www.reddit.com/r/AllThingsTerran/comments/1vmbzg/flash_mech_build_order_vs_drg/
But am also going to try out
http://www.reddit.com/r/AllThingsTerran/comments/1xdx6l/tvz_build_order_yumes_15_min_22_mech_push/
To be fair, I don't normally
lose against Zerg these days, so my perspective could be all weird and the timings in my head might be all wrong?
EDIT:
And Kretocs Mass Raven build on Habitation Station, though it can be shut down hard if it's anticipated.
http://www.youtube.com/watch?v=3lQId5CiXkM&list=PL6zS_SD7fCL30xDVeRK3Fq1_EgX0SYMNW&feature=share