Keep it simple with the fastest and easiest way to use your new-style belay device. On multi-pitch climbs, I like to take turns leading. I hate having to flip, or re-stack ropes at the belay, and after a stressful lead, I am always happy to follow a pitch. And as a naturally-cluttered person, I'll do anything to simplify things at the belay. That's why I like to take full advantage of my auto-locking belay device by using 'the swap'. An auto-locking belay device has become standard equipment on multi-pitch climbs, with nearly every company now making a lightweight device that can be hung from the anchor. These automatically lock off the rope should the second climber fall, but offer another, little-used advantage beyond hands-free belaying.
Simplicity - When swapping leads on a multi-pitch route, both climbers should have a hangable belay device like the Petzl Reverso, Trango B-52, or Black Diamond ATC Guide. The first climber leads the pitch and belays her follower like normal, by hanging her belay device from the anchor and bringing in rope in hands-free mode. When the follower reaches the belay, he should not bother with a daisy chain or other personal anchor slings. Instead, leave the desired length of rope out from the belay device to facilitate easy gear exchange or comfortable distance from the anchor. The follower can hang from the belay device--already in place-- using the rope, which was already tied into. The follower is locked off with a dynamic connection to the anchor, and avoids fiddling with extra gear.
Speed - The follower will lead the next pitch, and so he should begin to rack gear or quickdraws on his harness. The belayer should grab the team's second belay device off her partner's harness, and clip it into her own belay loop. The rope is already stacked with the new leader's end on top, so the belayer should immediately put her partner on lead-belay as he finishes racking his gear. The new lead climber is still hanging from the locked-off belay device he was brought up on, and now on lead-belay from his partner with the second device.
Swap It- When the new leader is ready to begin, he confirms that he's on lead belay from his partner, and then un-clips from the hanging belay device, grabbing it to bring with him up the pitch. The climbers have now swapped belay devices, and completed a simple and speedy belay changeover without having to re-stack the rope, use a daisy chain/personal anchor, or carry more than one belay device each on the climb.
A note from the VertiCulture Editor: Blake is one of my favorite climbing bloggers to follow. If you haven't checked it out yet, I recommend you heading over to the Travels and Tribulations of Blake Herrington. His Stikine Story is one of my favorites of the season.