Pros and cons on this swap, but overall IMHO the '11 turbo is a much more finished and comfortable vehicle.
Pros for the 2011 - 8 speed transmission, eliminated the need for a high/low range transfer case and makes for very relaxed cruising at 100MPH if you can find a place to do that. Much nicer interior, not prone to peeling soft-touch paint. Better HVAC. If you get one with the pano roof - the roof is actually useable without the glass exploding. Overall much better fuel mileage (city and highway). PCM has built-in bluetoof, and optional built-in Serius radio. Better and easier to use GPS. Drivers instrument cluster has one pod with an LCD screen that can be used for many functions - quite handy.
Cons for the 2011, transfer case can be an issue. Porsche extended the warranty on them for 10 years after in-service date, but on many 2011's that's now expiring. They don't all fail - perhaps 15% or so do. New case isn't horribly expensive with some shopping around (I've heard prices of $2,400) and installation isn't awful. My transfer case now has 106,000 miles on it - the original one. Some early '11 turbos (and /S models) had an assembly flaw from the factory in the VarioCam mechanism for the engine. With a bit of pressure applied Porsche made good on this - doing a recall for this and obviously resolving the issue at no customer expense.
And the '11 is lighter and faster than your '08. The difference in weight is noticeable in how it handles the "heft" of the car.