QuadraTrac II, which is standard on the Limiteds, is fine for deep snow. i have had two previous Limiteds, neither one had locking differentials and they were unstoppable in deep heavy snow, never once had any problem driving up my 1000 foot long driveway in fresh unplowed snow. the tires on my 2008 Ltd are much more agressive than the ones that came on my 2004 Ltd so i am confident my new '08 QTII Ltd will also laugh at deep snow.
QuadraDrive II gets you the locking differentials and yes if you are a serious rock-climbing off-roader then it is worth the extra money for sure. but for oridinary on-road driving? not needed if your tires are adaquate. i also dont like those tow hooks sticking out the lower front of the Ltds that have QDII.
good luck w/ your new jeep.
2008 Grand Cherokee Limited 4X4, Light Greystone Pearlcoat, Hemi, Tow Group, 18" Chrome Clad Wheels. Original owner, 20,000 miles
2002 Wrangler Sahara, black, 4.0L, 5-speed, Dana 44 rear axle with Trac Loc LSD, duel tan tops, Canyon wheels with Wrangler Silent Armors. 75,000 miles, 2nd owner.