I've owned both & hunting accuracy isn't a problem, both brands shoot better than anyone can shoot them in the field. Go with what feels best for you. As far as caliber, again we're rolling the dice. The 454 is a big time rocket, amazing power with flat trajectory & with the correct bullets can take anything on the planet, it's already done it many times over. Good bullets are the key to stand up to the high velocity.
With the 475/480 you are getting a bigger hammer, amazing knock down power with big heavy bullets that penetrate like crazy. I've owned both FA & BFR's & it's just like arguing Ford or Chevy, you choose what suits you best.
I've had a 10" 454, a 6" 475 & a 10" 41 FA, the last 2 I used in Africa with great success. The BFR was a custom shop 44 that shot better than expected & was a beautiful gun but I could not get use to the looks of that grip frame, a small complaint I guess but something that just bothered me to no end even though the gun shot great. I killed my moose with the 480 caliber, it will handle anything out there, if you need more than that, I'm not sure a 475 is enough difference really, just my opinion. Oops, took my Cape Buffalo with a heavy loaded Ruger 45 bisley & 325 gr hard cast, one good shot that went clear through & one finisher. Shoot what you shoot best.

Dick