The Black Diamond ATC Guide is a tough belay device and our favorite for multi-pitch climbing. It gets our Top Pick award, barely edging out the newest version of the old winner, the Petzl Reverso 4. It's more durable than the Reverso 4, better with thicker ropes (9.5-11.0 mm), and creates less friction for the belayer in auto-block mode. We know many guides in Yosemite and elsewhere that use the ATC Guide year after year. It catches lead falls well and locks off strong when a hanging climber needs to rest. That said, the Reverso 4 is an ounce lighter, so it's not easy to tell a clear winner.
In this review, we'll compare the ATC Guide mostly to other devices tailored for multi-pitch climbing. These include the Reverso 4, Edelrid Mega Jul, and Mammut Smart Alpine that all have dual friction channels and auto-block (guide mode) capability. If you don't multi-pitch climb and belay off the anchor much, we recommend the simpler tube-style version of this device, the Black Diamond ATC XP, along with the updated GriGri+ from Petzl for those looking for an active assisted braking device.