We run with ProAuto most of the time, but the timing for this one was off... just got back from two weeks in Colorado. And it's still too hot!
Pro is a great group to run with for HPDE. They're not as race oriented as NASA so things are a little more relaxed. They do have W2W race groups though. I run their Hot Lap TT series with our Miata.
Inde is a very fun track, easily the most interesting track in AZ. We've only run it once so far, but we're planning on going back in November with the Southern AZ PCA. Last year the weather was perfect in November. One thing that's kind of a PITA at Inde is fuel... the closest fuel off track is in Willcox, 12 miles away. They do have fuel at the track, but it's expensive. The way a ZL1 guzzles fuel on the track, it's an issue if you're not able to bring extra fuel with you.