I went with all Revelate Designs, because I assumed (correctly) that the bags would work together. In other words, the placement of straps wouldn't interfere when using multiple bags. If you mix and match brands, you may run into issues or not. All depends on the design. Buying over the internet means you don't have an opportunity to see exactly how they fit and interact on your bike. The only minor issue I ran into was with the Tangle framebag, which interferes with the water bottle cages, but I worked around the issue by going with smaller water bottles and moving one cage down with an adapter.