The GTD might be the first car I keep more than 2 years in a long time, depends whether there's something I want more around the corner.
I loved my MK5 Golf GT Sport TDI170 for all of 2 weeks when a bus clattered it. Thanks to a piss-poor repair and constant remedial work, ownership of that car was soured until I got rid of it for a Scirocco 140TDI (because I didn't like the looks of the MK6 Golf and the 170TDI CR engine wasn't out yet. As soon as the 170 was out, I wanted one, but waited until the 140 Scirocco was 2 years old. The new GTD blows the Scirocco away in all but looks and i'm drawn to the practicality too.
If a new MQB Scirocco comes out as fully loaded as the GTD and with the 184PS engine, I could be tempted back (maybe), but otherwise, short of going for a new generation Audi TT (depending on what it looks like) if wor lass eventually learns to drive and can drive the "practical" car, I could see me keeping the GTD for 4 years.
4 years PCP though? I would always aim to pay the same monthly payment equivalent to a 5 year outright loan, that way you should always have some equity from year 2 and onwards.