Yes, but I don’t know any of the details about why. I was wondering about this too.
D4 XP-L HI is more throwy than FW3A XP-L HI. It’s roughly 20 kcd vs 12.5 kcd. The D4 has more lumens and more reflector area, and the optic isn’t frosted.
Benefits of 4 emitters in a FW4A:
- More lumens
- Potentially more throw
Benefits of 3 emitters in a FW3A:
- Lower cost
- Compatibility with popular standard optics and popular standard MCPCBs
- Smaller head, without the need to make custom optics
- A proven and widely-loved beam type
- A bit lower power and less heat (which are both important on such a small light)
- Slightly better tint in low/med modes
What a lot of people would really like to see, though, is a FW1A with just one emitter:
- Much more throw
- Much less heat
- Lower cost
- Reflector-style beam
- Compatible with more types of LEDs
- Better tint in low/med modes
- (however, would probably be longer, and turbo might overdrive low-Vf emitters when a high-amp cell is used)
The slightly lower Vf of a 4-led light compared to a 3-led light doesn’t really improve efficiency on this type of driver. It mostly just makes more lumens and more heat. There’s a larger voltage overhead, but this isn’t converted into more light… it just gets burned off. To get a meaningful efficiency boost from extra LEDs, it would need a buck or boost driver.