Is there anything else that I should consider?
I've got a Montane Dyno for riding it (I like it)- its not for riding duties, its keep in the boot of the car, throw on when loading bike/unloading, walking down to shop at night to buy more beer, out and about etc etc.
The Rab Photon just looks like a bin bag to me.
Ideally down to -5ish with a fleece underneath and will last years. (I have a Mammut softshell thats getting on 10yrs old and still mint)