FP is just covering their butts as best they can. The only real issue is the mesh filter in the oil line, as there's actually a TSB for it from Subaru. I removed my as a preventive measure, but mine had no problems.
The restrictive ports in the lines and bolts are not as big of a deal. The only reason to require a lot of oil flow would be for cooling. The FP turbo is water cooled, so it shouldn't have much issue with heat. If you run a turbo that wasn't water cooled, then you could have issues with the oil getting too hot if the flow wasn't high enough, or you didn't let it cool down after a hard run.
Personally, I wouldn't worry about the OEM banjo bolt. Tons of people run big turbos without upgrading the banjo bolt, or removing the inline filter without problems. I guess it comes down what you want to do as preventive measures.