There's a third way: a switched-mode power supply with regulated output current. This is used in most better-designed flashlights (which doesn't always correlate to price) and can be used by anything else that needs to drive an LED as well.
The article doesn't discuss what technique should be used for "constant current reduction"; it probably shouldn't be a linear regulator where efficiency is a priority.
PWM is less annoying if the frequency is very high (several kHz), though I'll leave it to people who research the topic to speak to health effects.
In the world of LEDs, a switched-mode power supply with regulated output current is called a "constant current driver". I assume that's what this calls "DC dimming".
A linear regulator might also reasonably be described as "DC dimming" or "constant current". The article is only concerned with flicker so it doesn't discuss efficiency.
There's a third way: a switched-mode power supply with regulated output current. This is used in most better-designed flashlights (which doesn't always correlate to price) and can be used by anything else that needs to drive an LED as well.
The article doesn't discuss what technique should be used for "constant current reduction"; it probably shouldn't be a linear regulator where efficiency is a priority.
PWM is less annoying if the frequency is very high (several kHz), though I'll leave it to people who research the topic to speak to health effects.