harddrive123:
The resistor is there as an energy absorber for the voltage difference. I see no way that oscillations could start; that only happens when 2 regulators are truly in parallel with no resistance matching.
In real circuits there is ALWAYS resistance in the connections (granted usually much less than 10-20 ohms), but never-the-less such oscillations do statrt. Further, while what you propose may work most of the time, what is the end result if your circuit is connected to a source that was produced by some shady third world company who cut all possible costs and removed every thing in a normal USB design that you are relying on to allow your approach to possibly work?
harddrive123:
I'm aware of germanium diodes for smaller voltage drops, but I want 5V not 4.3V or 4.7V.
Getting schotky diodes with voltage drops of 0.15V is not difficult to find.