I'm not sure that I can make a fair comparison having never ridden either of them.
Please feel free to add or dispute my points:
D16RR Pros:
1. Exclusivity
2. V-4 or L-4 if you prefer. Either way, I love V-4's most, Twins, second, I-4's 3rd.
3. Probably a cooler bike to have long term as so few will have ever owned one.
D16RR Cons:
1. Price still north of $40K for bike without warranty.
2. Older technology (awesome 3 years ago, slightly behind 2012 Panigale).
3. Insurance premiums are guaranteed to be high.
4. 16" rear wheel limiting tire choices.
5. Upgrades are prohibitively expensive due to high MSRP of original bike and low # of units.
6. Expensive maintenance.
Panigale Pros:
1. Same or almost similar power with 10lbs less weight
2. Cheaper, even the Tricolore with full exhaust and all the carbon bits as options.
3. 2 year warranty.
4. Cheaper insurance.
5. Cheaper upgrade/aftermarket parts.
6. Newest technology and electronics.
7. Cheaper maintenance.
Panigale Cons:
1. In 10 years, I would probably rather own the D16RR.
2. Less exclusivity.
3. Wish I could think of more, but I choose this route, so I am probably biased