Let the test drive decide. Relatively speaking the newer generation Porsche's are pretty reliable and it sounds like you make enough money that if you got hit with a big maintenance bill you would be okay.
You just need to decide if you want to daily drive a convertible 12 months out of the year in Kentucky. The BRZ will be a lot more practical 12 months out of the year and has more room for stuff.
Pretty tough choice and I don't blame you. And how dare you guys make fun of the Elise