I had the same choice a few months back before I ordered my PPC212 which is awaiting the Dual Terror to use with it.
I went with closed back for the following reasons:
I found my Fender Deville 4x10 too bright and open
The CB version is stilll available in Ltd Edition White to match the DT
I have been very impressed by the UK manufactured bass and guitar cabs from Orange. All built extremely well, with attention to detail. Yes, they weigh a fair bit, but the thickness of the wood seems to help with that dark Orange sound.
On the forums I use in the UK, If I ever wanted to selll it on, the CB/UK made would sell a little better. So better resale value, for me anyway.
I often find you get what you pay for. Pay a little extra, get what you want.
Closed back cabs seem to be used by most of the bands I listen to, including the bands that use Orange cabs.
I wanted a more focussed, tight, and 'heavy' sound, even though I won't be playing really heavy music. I use a USA Tele, and as much as I love how snappy and bright it is, its always nice to give it a little bit more ommpph in the low end and add a little darkness to it.
Don't get me wrong, OB cabs are great, and certain amps as mentioned above just sound correct open, (or half open) but I wanted a setup that was just a bit bigger than a combo, all Orange, that had that low end thump. My Fender combo was great for cystal clean sounds, but sometimes the sound just got lost.