Simon Dyer wrote:
Since it pulses the LED, greater
perceived brightness can be acheived at great efficiency.

This is not true of the high brightness white LED types. The original
LEDs were more efficient when pulsed because the luminous efficiency
peaked at high currents, therefore constant current pulses at this level
produce an integrated light using less current than a DC current for
that same light level. This is not the case for the white LEDs. The
luminous efficiency peaks at low current levels like 5mA- so you
actually make the circuit LESS EFFICIENT by pulsing at high current
levels. The switching circuit referenced exists solely for the purpose
of voltage boost from low cell voltage battery technology to the higher
voltages required for the white LED.