This variant of the Montblanc Heritage Spirt Perpetual Calendar was officially launched in Watches and Wonders Hong Kong 2 weeks ago. We saw some pics of it already as it was pre-announced before the watch fair and some of us already saw it at the boutiques.
I was fortunate to have some time to play with this watch in a private session with Mr Alexander Schmidt, Montblanc's global director for watch category.
The key difference is a whole new dial, which is made of smoked sapphire. It is not a skeleton watch as it does not allow us to see through the movement. Instead it allows us to see more parts of the intricate movement of a high complication, i.e. the perpetual calendar.
The smoked sapphire dial is very nice in the metal. My pics can't do it justice. It is clear yet has a grey-brown hue on the smoked sapphire dial. This brownish hue compliments the red gold case very nicely and gives a "smoky" romantic feeling to the dial when I gazed upon it for some time. It was difficult to give it back to Alexander! 
As many of you had pointed out, the smoked sapphire dial makes the sub dials feel less cluttered around the middle of the dial, another clever design decision I feel.
Some pics to share here. A sophisticated looking watch with a high complication to boot yet at a very attractive price point. An elegant case design at 39mm. Good size for a dressy QP.
Hope you get to see this in the metal. Let me know how you feel if you do 
Cheers
Robin 


With some reflections to see the smoked sapphire dial
On my wrist when I first saw it.