Most of the EFI cars of the 80's-90's used return style regulators. The newer stuff uses an on-demand style regulating system that controls the pump output to regulate pressure. Sounds simple but requires a significant amount of complexity for the EFI control system, such as a pressure transducers to measure FP and give feedback to the ECM and modulate the fuel pump. The computer will also have correction algorithms to correct for fuel pressure discrepancies that are inherent of those systems.

So in general, if you have a return style regulator with a huge pump to support a lot of power, it will generate a lot of heat in the tank due to return flow recirculating but will generate the most stable fuel pressure and in turn, the EFI tune will be more stable. The work-around solution is simply to have PWM control on the pump to limit the amount of return flow and basically giving you the best of both systems. A lot of EFI systems have that capability.
AG.