I own the 480 version of this revolver in 6.5 and have found it to be solid and very accurate. I have found no issues with excessive muzzle blast and all my hand loads are pushing a 405gr hard cast at just about 1230FPS and shoot sub 2 inch groups at 50 yards. I know its not the 454 you are looking at but as far as build and accuracy, these are good revolvers. I have a buddy who has the 4 5/8 version in 454 Casull. I have shot it and love it as well. I have a SRH in 454 with the 6.5 inch barrel and the velocity difference is negligible between the 2 using the 300GR XTP Mag loads. If you can, shoot both variants and buy the one you like. I don't think you can go wrong with either barrel length. Just my 2 cents.

Good Shooting!