The compactness question
DCF850B is DeWalt’s ATOMIC three-speed quarter-inch hex format. It belongs in the comparison when a shorter body addresses a repeated approach problem on suitable fastening. The bit, socket adapter and battery still contribute to clearance, so the front-to-back figure is not the whole tool in use. We have not conducted cabinet-clearance or fastening-speed tests.
Avoid forcing delicate work
A compact impact driver can still damage a screw or finished surface if the method is wrong. Modes provide operating control rather than measured torque. Cabinet hinges and fittings may be better suited to controlled drill or hand driving. Owner claims that it replaces their drill reflect their own work; they are not a universal recommendation to use impact action for every hole or screw.
Value for a battery owner
Existing compatible DeWalt power can favor the B bare-tool purchase. Compare DCF860B when a different supported fastening requirement or documented control feature matters, rather than assuming a higher torque figure is always useful. Include the correct impact accessories, charging and power in the budget. An apprentice should still identify which equipment is personally required before buying a second driver.