A little background is in order.
Yes there is currently a model of light being sold named the FW3X, which is the FW3A light but factory outfitted with the Lume1 driver.
In the context of Loneoceans’s guide that was referenced, the term FW3x refers to the FET+1+7 driver first used in the variety of FW3_ based model lights (e.g., FW3*A**, FW3*T** FW3*C*…) lights. Note that the current batch of FW3_ lights are reportedly coming with a different driver (e.g.FET+1).
Typically (but not always, depending on design and parts used) a Boost or Buck driver is more efficient than a linear driver. I believe it to be the case with the Lume1 driver.
The FW3A and Lume1-FW3X Driver threads will have much more detail.