I don't really see the problem. They have different uses, so I'd always carry both with your FO.
SoF to hit groups of enemies. DMC isn't really going to be problem, since you're only using it to demon anway.
BR to hit one target, with rifle range (Zus, Gi Gues, Dorphons...).
However don't expect BR to be alot more accurate then SoF. For some single targets it's even better to rely on the SNS glitch with SoF – Delbiters or Ill Gills for example – then try to Demon with BR. You're not going to hit those even with 50 hit. To be honest Fomar misses so much, even with high hit, that I'd highly recommend another class anyway. Or hope for Godrics cloak to get fixed - it's not going to happen though because that would make too much sense.
Also yes, you can add hit% with PC to your BR.