- No, this driver is less efficient than the LD1 in the lowest modes. This driver is also completely unregulated. It is a very different type of driver than the LD1 which is a linear driver.
- A driver intended for use in similar roles to the LD1 is this one: 17mm double-sided & 20mm+ single sided 4Amp+ linear driver [A17LDQX]
- Other DIY drivers with good efficiency in low and moonlight modes are my A17PZL (17mm 8x7135 with Zener & dual-PWM) and RMM & Mattaus’s Moonlight Special V2 (post #1447).
Depending on your needs, I’d recommend looking at the A17PZL. It’s simple, well understood, and handsome. 
(RMM’s Moonlight Special driver may be easier to build by reflow, but I think that the A17PZL is probably going to be easier to reflow now that I’ve added the scallops around the edge.) The downside is limited current: Without stacking 7135’s you won’t do better than 3.04A. The first driver I linked to, tentatively named A17LDQX, is experimental and should be capable of the same drive currents as the LD1. Unfortunately it is much less compact than the LD1, requiring a two sided board with plenty of components on both sides.
For a better understanding of some different types of drivers we use, please read this thread by lagman: Understanding the difference between Linear, Buck, Boost and Direct Drive drivers.