I don’t begrudge them as a concept to save 0.2w but there’s something pleasingly HH about the angles of a chain outline when a bike is in 53x11 and the OSPWs ruin that aesthetic. Therefore they are not HH in my opinion.
I've read somewhere that most savings come form less tension on the cage, savings from the pulleys itself are like 0.2 watts.
Firmly believing this since it aligns with my views on stupid pulleys and chains too short as a bonus.
Drivetrain efficiencies are not a scam. OSPW have been proven to achieve drivetrain efficiencies. Up to you whether you need them.
Aesthetically, I think OSPW identify a certain type of rider, who is completely aligned with HHSRB. #IMO