Love, love, love Austin, I tried to PM, but your mailbox is full...see inside.
I've actually lived there twice, my daughter lives just minutes south in Buda.
I have a dear friend who lives in Westlake Hills, up high with a wonderful view of the hills and city.
We lived a few minutes west of Westlake Hills in the hill country until 10 years ago.
The only things I really have against Austin is traffic which is really bad, and that it's hard to find a one-story house, most are two-story. Also very small lots, I don't know how it is in Nashville. The housing market seems to still be fairly strong there, not such good news for people moving in from areas where it has tanked.
The weather can be brutally hot in the summer with high humidity, but not as bad as here in Florida. Winters are generally mild, but once in awhile there's a skiff of snow or an ice storm.
I really hope you have a chance to look the area over before you have to make a decision. If you do get to go, don't miss the flagship Whole Foods and Central Market. Austin is a foodie's dream, also good, reasonable restaurants. Sigh, did I say I love Austin?
Truth be known, if we do move back, it will be in an outlying area where you can still get large lots, but Austin is a great place to live. One of the reasons it's grown so large is students at the University of Texas graduate and don't want to leave, lol. Then so many of the high tech companies from the silicone valley moved at least some of their operations there. I think about every large computer company is represented.
That's all I have time for right now, as with any area, there are downsides, but I do so hope you can visit and check it out for yourself. Let me know how it goes.