I've had my Desmo since new and ride it all the time. Every single ride is a spine tingling adventure from the moment you hit the starter button! it's one pissed off angry beast, but the harder you push it, the better it gets. Pure pleasure on the track and street.
I only have 200 miles on my Panigale so far, and have only barely sampled it"s power. It feels smaller, more nimble, more civilized. Initial impressions are that it doesnt seem to have the same punch as the Desmo. The technology is very cool and it's very comfortable, you could easily ride it all day.
My two cents: You don't buy either of these to be practical, it's all about the visceral thrill. To that end, it's the Desmo hands down, That's the real E-Ticket ride. The Panigale is Dr. Jeckyl, the Desmo is Mr. Hyde. You already know deep down inside which one you really want.