Buy the newer car given your budget. The latest Porsche is always the better one.
Tiptronic S (only 5 speeds) is generally rubbish on Porsche sportscars, but on the Turbo it is faster than manual and it has the overboost function. If there is one 911 that someone would accept tiptronic, this is the 997.1 Turbo. But still no match for PDK.
The DFI/PDK car should be more economical. As to comfort and costs I don't think there much difference between the two.
Snow? I have no idea!
--
"Form follows function"