Why do you need a rope bag, you might ask; why does it matter if your rope gets dirty? Well, whether you are going to Smith, the Cookie or the Red River Gorge, keeping your rope clean is more important than you might realize. When dirt and grit get into your rope, it dramatically shortens the lifespan by abrading the fibers in the core. This can give your rope soft spots or encourage the sheath to separate from the core sooner than might normally occur. Also, if your rope is dirty, not only does it negatively affect your rope but your other gear as well — all the bits of dirt act like sandpaper. Ask any climber who frequents Indian Creek or Smith Rocks to show you the grooves in their belay device. The draws that hang on Chain Reaction can be terrifyingly worn through. Not all climbing areas are the same — areas with drier dust tend to be worse than moister areas with more compact dirt — but a rope bag will extend the life of your rope no matter where you climb.
Protecting the rope
The most important part of any rope bag is protecting your rope. We defined protecting your rope as keeping it off the ground and out of the dirt/sand/moss. With this in mind, we felt that rope bags that came with tarps that were bigger and would lay flatter and thus cover more ground were better. The 4' x 4' and 4' x 5' tarps seemed ideal, not too small and big enough that when you pulled your rope from the chains, it would mostly land on the tarp. That size also gave plenty of room to comfortably flake our ropes onto. The smallest tarps were 3' x 3', and that seemed a little small. We had to work a little harder to keep the rope on the tarp while flaking it. After our tests, we thought the Metolius Ropemaster just edged out the Super Chute. The Rope Ranger/Ropemaster tarps were only marginally bigger than the Super Chute, but their ability to lay flatter gave us more room. Not far behind was the Black Diamond Super Slacker. The Super Slacker tarp, while it wasn't bigger than those of the Super Chute or Rope Ranger, felt bigger due to its rectangular, flat-laying nature. The Metolius Dirt Bag and Porta-Cord both sported 3' x 3' foot tarps that were better than nothing but that we wished were bigger.
Ease of putting away the rope
The next thing we compared among rope bags was how easy it was to put each rope away. Less messing with ropes equals more climbing. Plus, one of the major reasons people buy rope bags, besides keeping their rope clean, is keeping their rope well managed so they don't have to re-stack it every route. We thought the easiest rope bags to put away were the Black Diamond Super Slacker and the Black Diamond Super Chute, each for different reasons. The Super Chute has a more common "burrito" style closure. What made it easier than the similarly-designed Rope Ranger and Ropemaster was that it had the largest diameter opening that its super-spacious, articulated tarp rolls into. The Super Slacker was even a little easier, but they are both pretty dang easy. For the Super Slacker you simply fold the tarp in half, fold it again, cinch the ends and zip it closed, a design that has stood the test of time and is brilliant and easy.
We tested how well each rope bag compressed to fit into our packs. Although all the rope bags we tested featured some sort of carrying strap, over half the climbers we know store their rope bag inside their packs. Nearly all the tested rope bags featured a compression strap, some of which worked better than others. A few bags featured more durable metal buckles. We thought that the Arc'teryx Pali was the most packable rope bag, with the Metolius Ropemaster and Rope Ranger just behind. The Pali has a nice, small, compact shape with one compression strap. We gave it higher marks because it was designed with packability in mind. Arc'teryx designed it to fit perfectly into a Miura 50. We found that even if you didn't own a Miura 50, it fits well into most 35-55L packs. The Metolius Ropemaster/Rope Ranger had nice compression straps and were a little shorter than the similarly-designed Super Chute, which made them easier to pack.
How nice each bag was to carry around
Even if they carry their rope bag in their pack, every climber will inevitably throw the rope bag over their shoulder while moving between routes or crags. The Metolius Porta-Cord was by far the most comfortable to carry in backpack mode. It was so comfortable that for routes on Washington's Goat Wall east of the crest in the North Cascades (an area with a 30-45 minute approach and 5-11 pitch sport routes) it was the only pack we took. Some climbers never put the rope bag in their pack at all. For climbers who nearly always carry their rope bag in their pack and never wear it for more than 10 minutes, all the bags we tested were pretty comparable.
The ability to carry other things
It is super convenient to toss in your rock shoes and your quickdraws, pack it up and move to the next route. This is especially true for areas with a lot of routes close together. The Black Diamond Super Slacker was our top choice because we could easily fit a 70m rope, harness, 15 quickdraws and rock shoes and still have room for a water bottle, guidebook or other items. The Super Chute was almost as easy to pack away a rope and a ton of stuff into. Not too far behind that was the Ropemaster, still able to fit a 70m cord with shoes and draws. The Metolius Porta-Cord was by far the most organized with its many pockets. With a 60m rope, it was big enough for your shoes, some draws, water and a snack. With a 70m rope we couldn't fit both our rock shoes and the quick-draws, but we could fit one or the other.
A feature that earned a bag higher scores was a dedicated small place for easily lost items like keys, wallets, and cell phones. Another nice feature was a place to tie the ends of the rope to, keeping you from having to re-stack the rope as often and keeping you from losing the ends, especially nice for older ropes where the tape has come off.