Had a look at them during my lunch break today. They're just as impressive as I was expecting, but I'm disappointed they're going to discontinue the Mk7 Transit.
Even the lwb Custom (which is a similar length to the outgoing mwb Transit) has a smaller volume than a swb Transit. As someone who considers the Transit the perfect size for his business, I'd be vary wary about downsizing.
There are obvious improvements everywhere else, and although the cabin is a bit smaller with less handy dash-board stowage space, it makes up for it with nifty tricks such as a folding centre seat and underseat storage.
It's too nice to be honest. As a works vehicle it needs to be able to take a few scrapes (not that I've ever given my van any!) and multidropping in a Custom would be a bit like battling through the Amazon in a Range Rover - epic vehicle for the job, but you'd ruin it.