What affects the PID is that a proximity focussing RICH detector with C6F14 radiator and CsI readout after an expansion volume was proposed by Lars that serves as a tracking and a PID detector as well and that could replace the DISC DIRC in the same psition.
Klaus Föhl performed some calculations that he presented in the Hadron Cherenkov Forum and (with some plots) in this VRVS meeting.
According to his results a proximity RICH in the Target Spectrometer could reach a 4sigma kaon-pion-separation up to 5 GeV/c, where as the focussing DISC DIRC on the same position reaches 6 GeV/c, the TOP-DISC-DIRC 4.5 GeV/c (particle 10 degrees). Simulations from Bertram Kopf show that the kaon in the forward region of the target spectrometer go up to even higher momenta than 6 GeV/c.
Of course the possible detector types have to be compared more carefully which will be a task for the Tracking TAG and for us the PID TAG as well. Please see the contribution that Klaus Föhl will add to this minuits. In Genua he will present as well.