Mark, you might be right about a stand-alone phones or tablets. However, I know that Foreflight provides a very nice AHRS display when plugged into a Status or Sentry. Dynon also makes a slick portable EFIS with AHRS. It measures 3.5" x 3.25" x 1" so you can easily hide it in a pocket. With so many cheap and affordable AHRS devices on the market, they're going to require cavity searches in order to actually keep them out of cockpits. Heck, it's getting pretty difficult to put together a modern panel without AHRS. As another member mentioned, he has 3 different AHRS devices.

I'm trying to imagine what would happen if a pilot deactivates AHRS to comply with contest rules... and then they have an accident involving IMC. I wouldn't want to be involved in that lawsuit.