Rapha, nice but a bit pricey?

Hmmm... TBH I manage quite well with a base layer, jersey, arm warmers, thin rain jacket. That said I have found the cold on my chest is leaving me a bit wheezy / short of breath sometimes.

Decisions, decisions. I just worry that it won't see enough use.

I think you will find plenty of use for it as you won't need to wear a lots of layers, just plop in the jacket and ride away instead of fiddling with arms warmers, jersey, base layer etc. (I find the Softshell + base layer to be warm enough after 10 minutes of riding).