To each his/her own. All OFRs come with brass blocks and always have. They are silvery colored because they are plated. If you compare an OFR to a Gotoh FR side by side, in your hands (so you can look at all surfaces) it is plain to see that the OFR is ground and polished better before being plated.
The base plaits of the two are made using different methods.
The OFRs base plate is made using a cintering process. This process uses metal powder that is pressed and heated under extreme pressure (without melting it) into the parts shape using a die/mold. This make for an extremely hard part that is very wear resistant.
The Gotoh FRs base plate is stamped from a sheet, bent to shape and then hardened.
One method is not necessarily better than the other in this situation, just different and due to this, they sound different. I believe the sadles are made differently as well. The OFRs I think are made the same as there base plates. The Gotoh FRs are cast. This also imparts a different tone.
In the end, which one works best for YOU is all that matters. Some time you may have to tweak something a bit to get it "Just-So".
At this point I am solidly on the OFR side of the fence, but we will see after I get some experience with the Gotoh FR.