I agree with M! that an extended warranty would improve resale price of used QPs, as perceived build quality issues must still be one of the biggest sales limiting factors for Maserati.
The trouble with the QP is that the target market is different from Coupe/Spyder/GS, i.e. QPs are aimed at the corporate market. In corporate-land you always want to have a new car, because depreciation is a good thing (depreciate or pay more corporate tax).
Incidentally, I was near to buying a Coupe, but ended up getting a 20 month old QP for only slightly more than the 7 month old Coupe. Retail with its options the QP was £83k and I bought it for £28k less with 10k miles on the clock. £28k in 20 months... ouch. I would expect (hope?) value to drop £8-10k per year for the next few years, but there is no way to tell as the QP was intro'ed in 2003 and the oldest used on the market are early 2004 models.
After driving the QP, I thought the drive was nearly as fun as the Coupe 10% of the time when you are pushing to the limits, but much more refined 90% of the time while cruising. You get much more car for your money with the QP than the Coupe.