Mark,
IMO, the single biggest advantage that PS3 engines have over PS2 engines, is that the DSP (digital signal processor) is an FPGA chip as opposed to an ASIC.
The FPGA is a much faster chip and provides significantly improved DCS signal strength.
This is also the single biggest difference between the Rev. L TIU and all previous model TIUs.
This and a whole lot more is all in MTH’s “The DCS O Gauge Companion 2nd Edition", available for purchase as an eBook or a printed book at MTH's web store!