My P85 has the Sound Studio package and I love it! I think it is especially good with digital music from an iPhone, etc. There are songs I have that sound amazing inside the cabin, better than anywhere else I have listened to them.
I am a sound nut and I love it...don't be dissuaded by all the criticism of the SS you read on here. Judge for yourself, with your own ears
I think it is worth it.
One warning I have is satellite radio with the SS is disappointing--but I think this is mainly a subpar antenna setup. Lots of dropped out signal. I know Tesla is working on this--I'm confident they will make it right.