I have the D18 & a couple of Sofirn SP36 lights, all work well but the D18 is more floody even tho I have narrow optics used for the center 6 LED. D18 is a bit wider than the 36s & they are a bit longer, all use 3 18650s. My D18 is rated for 10k/L, the 36s 5.5k/L & 8k/L; both with good flood & a bit longer throw. The real up side for Sofirn is you can get both versions of the 36s for under $100 [$48eaw/o battery] & they recharge in the light so no worries about mixing batteries. With the sale Sofirn has that ends today the 36 cost 46$ with batteries & is the way I'd go if money was even a little issue in making the choice