limiting that rush has less to do with protecting the PSU and more to do with not tripping crappy breakers if you plug them in coincident with the peak of the mains sine wave.
This has not been true since breakers were introduced. One of the principle advantages to the breakers was a magnetic *and* thermal capability. This allows breakers ( even crappy ones ) to handle inrush of massive machinery.
If you are feeling brave, you can try the following experiment ( I already have with several different types of breakers ): Take a dead short (Large gauge wire like 8 AWG or 6 AWG. Hook it up to a power transistor controlled by a microprocessor. International Rectifier makes some 100A jobbers that can handle spikes of up to thousands of Amps for less than 10ms bursts. Set up a zero cross detect on your microprocessor and turn the juice on through the dead short for 1 full wave of 120VAC. Hook up an o-scope to your mains and check the line voltage as you turn this critter on.
What you will get is one full cycle of severely browned out mains (might drop as far as 10Vp-p. across a 1mOhm load ). For those astute at math, that would be 10,000Amps at 10Vp-p, or about 60 kWatts RMS. As long as you only do this for one full cycle and no more, you will neither blow the breaker, nor significantly heat any of you components. The reason for this is because breakers are mechanical devices and have a specified amount of time before they can "react" to overload. Even their thermal shutdown takes time. Long story short, a standard 15A wall breaker can dispense about 15kAmps for 10ms without tripping. That is far more than the transformer at the pole can handle, and its own internal resistance becomes the current limiting factor. A good line supply will provide you with about 10kAmps before the current limiting drops the line voltage significantly. A typical residential supply will only dump about 1000 Amps before significant drops in voltage. Either way, the breakers will not trip no matter what you do, as long as the entire incident is shorter than 10ms.
This design is very much on purpose. As I have seen, and what these experiments demonstrates is that in-wall wiring, breakers, and utility company equipment are not seriously threatened by short power spikes, so they have no reason to try to protect against them. The breakers in your house are there to prevent enough power from flowing through the wires in the walls to cause them to start fires.
The inrush can however severely damage switching power supplies. Many of them are built to just barely handle the voltages they are designed for. This is done to save money and weight in the extremely competitive mobile power supply market. This market is so competitive, and the margins are so thin, that they will do almost anything sketchy they can to shave pennies off the design. I have personally seen transformerless designs that were built assuming one of the two main lugs was neutral. If they are plugged into a reverse polarity outlet, they short the hot line to the ground directly... This is a common design used on many different power supplies, and is one of the primary reasons you should never open one of those supplies while it is powered. Even in the lab the damn things are dangerous.