Great thread, thanks for starting this one. I was actually about to do the same thing by taking my 990 to AF1 and getting a dyno tune, they told me the same thing and I'm not ready to drop $800 for the work right now (EDIT: that's for the new ECU + dyno time, I'm rounding up).
I am not too far from ya (in Austin), I have done the tune on mine I have the cable so your welcome to come up this way and you can try out some tunes, if it doesn't work out you can always go back to stock map, that's the beauty of TuneECU. I would love to get mine professionally done, but I can't afford it right now.
Just bring some beer