The current limits of approx 20MB/s seem to be software based. Downgrade to FW 4.21 or below and it will get approx 50% faster.Ah yes sorry, I made a mistake on the calculations between bytes and bits, so it's because of the limitation of the transfer speed of the hard drive itself and its performance and not the SATA interface, and maybe the performance of the console's CPU.
I think someone with the skills could figure out what changed and bring that 50% speed increase to newer FW but no one has done it so far.