I had this option on my 02 LTZ and hated it.
Why do I need to know that my rainsensor is working in dry weather? It annoyed the cr@p out of me when it would wipe when it didn't need to and visa-versa and I couldn't control the rate.
Just another one of the extra's that really isn't needed and isn't very value added. Intermittent/delay wipe is more than enough. It's very efficient and works like it should.
Okay, I'm done ranting.