If you are running heads up, get every ounce out of the car type events, I am all for the sensors and data they can provide.
If you are bracket or index racing I do not think they should ever be in the car. All you need them for is one good weekend of data gathering and then use the data with todays ignitions to make or write the "perfect map" or timing curve to achieve the perfect run over and over. Is it a full proof science? No. I believe it is a hell of a lot better than reading weather from day to day, tuning and dialing or setting up for your index without it. To each his own I guess. I just dont agree with the sensors ever touching a car that is in a bracket type event.