I think the perks of this over a regular Cayenne are not necessarily so widespread in their appeal, but perfect to to those that fit the bill. In Ontario, having access to the HOV lanes is one thing. For another, if you DO have an at-home charger capable of filling it overnight (or at work), then 22km-ish of range will likely take you most, if not all of the way for where you need to go (without limiting ski trips on weekends, etc).
I think it's a great offering, though a niche product with limited appeal to the masses. The same can be said for the 911, with its limited utility and high (relative to a hybrid) fuel consumption.
Good on ya, Porsche.
Odd choice re the Supercharged engine though - I mean, Porsche uses a 3.0 turbo (albeit a twin), so why source the Audi unit? And since that engine is being phased out, will the E-Hybrid get updated to the new 3.0 turbo unit used in the S4, etc. perhaps?