To me the main plus of this jacket is the low (ish) weight relative to degree of insulation, coupled with the stuffability. Don't get me wrong I love this jacket, but, removable hood I hate & don't see the point. I also have an old Photon & if the best of the Belay & Photon were to be combined it would be the better of the parts.
Build quality is ok - but I've had two draw strings go within 1m, the material is fraying at the cuffs where the velcro adusters fix to the coat rather than the velcro, it also feels like the wiring in the hood is close to piercing the material. But Rab continually improve their products & have repaired my coat.
As for actually using it when you're belaying it certainly could do the job - instant warmth, unpacks in 10 seconds - the zips open from top & bottom so it would fit around a harness if you open the zip from the bottom.
Great jacket - by far my favourite, despite the above, but lose the stupid detachable hood.
(Written by: dvb123)