Tempting, but not necessary in my case. I think the most likely candidates for an upgrade are:
• Those who've been waiting for a Model X simply because it has AWD.
• Those who wished they'd ordered their first Model S with more options and a bigger battery than they did.
I'd be quite happy if I could purchase the new front seats for my 2013 P85, in addition to getting the rear suspension upgraded to the (pre-D) 2014 P85 specification. Some of the parts back there were upgraded since my car was built.
As tempting as the upgrade to a D is, I got along just fine last winter in Vermont with RWD. I even took the car skiing several times. Never got stuck. It's worth considering that there's a lot of new hardware on the D that's yet to be proven long-term. The braking system is entirely new and incorporates fewer calipers per rotor than the previous Brembo system. First, I'd like to see a few thousand of these cars with 10,000+ miles on them. Consumer Reports should have another go at it.