@Zane O. Here in two cents from the Amarillo area: Amarillo is a unique place and people that don't live here don't understand that. In the same way that Boston and New York seem like the same place to many Texans, most outsiders think we are all the same place too. Texas is a large state with numerous different local economic drivers. Whats happening at BSA & NW Hospitals, AISD, cattle, cotton, wheat & corn, and most of all PANTEX, trumps anything else in Amarillo. Those places host many of our high income earners. Especially in the demographic your house caters too, Pantex, agriculture, and the hospitals have a lot to do with that market. If you hold, my biggest area of concern is the new development at Hillside & Soncy. Im not sure how fast they will get that done and if it will provide too much competition for your house. To me, this new development looks like its bigger than we can support and could create oversupply.
I love the idea of you living in a flip and aiming for 2 years to get the tax benefit. Being that our economy is the tortoise and not the hair, I would expect the tax savings to be better than the other benefits as long as we don't create too much supply in this time. The fact that you have a relative in the industry, I would have been keep an alert eye out for you on the price of high end homes as the development takes place. You can always aim to hold for 2 years and list it sooner.
The reason why some are saying you don't have to factor in the holding costs into your profits is that it sounds like this will be your primary residence. If so, you have to live somewhere. Assuming if you didn't own this, you would pay something similar, you can somewhat exclude the holding cost from your profit projections. However, if you next primary residence will be much smaller, you will have significant savings on property tax and insurance in a smaller/cheaper place.
Overall, the numbers look decent to me. I haven't lived in Amarillo forever, but I have minimal fear of what the oil price is doing for our local area. My concerns rest with Pantex (which seems very stable at the moment) and the new Town Square development.