Thanks Jammy...
OK I still think there must be something I am not taking in about this car... you say 'it would not make sense as a private buy' - but it has the same performance (to the point of makes no perceivable difference - or if you look at the OP post here - better performance) as my GTD (DSG) yet its 50 quid cheaper to buy - and as most of my journeys are 25 miles or less its going to be doing the equivalent of 165mpg on 90% of my mileage.
Whats the issue? - it looks like a no brainer to me! 
It's just my opinion, I'm often wrong
I suppose if you can really make use of that 'plug in' 30 miles and you can live with the smaller boot then it could start to make sense. Standard petrols make more sense on low mileage/short journeys anyway so that would tip it in your favour too. For me I'd want to understand a) what the mpg is like if you don't plug in for say two weeks and b) in a similar vain, how effective the recharge mechanism is via coasting/braking.
They do warrant the battery for 8 years too so there's no worry from that point. I'm not sure how the PCP and lease deals will work out, I can't imagine the residuals being quite as strong as the GTD/GTI due to a few unknowns at the moment. That might sway the argument back to a GTD.
I'll let you know when/if I can get a demo on our lease scheme and report back.