One of the questions that seems to be coming up in forums lately is what happens when you use beads from different manufacturers. It's one of those things that I never think about, because I like the differences in texture that mixing manufacturers can give you. Others want their beaded braids to have a "seamless" feel with all the beads as close in size as they can get. I ended up with some down time (and a new photo light tent to test out) so I worked up a few samples to help you decide what would be best for your projects.
I've used size 8/0 seed beads from all three of the major Japanese manufacturers: Matsuno (aka Dynamites), Miyuki, and Toho. The braid is made with C-Lon/S-Lon cord, size Tex 210/0.5mm/#18/regular. I chose these materials as they are the most commonly used for beaded braid work and are representative of the results you would get with size 6/0 or 11/0 beads with the appropriate cords. Size 15/0 beads have fewer size differences across brands so the results would not be so dramatic as they are here. I chose not to include Czech beads as their sizes change more based on batches than manufacturer and they are more variable in width than the Japanese beads. Each sample has 6 beads per cord. As always, I loaded the beads onto the cords without culling (sorting), so there may be highly irregular beads in the samples I wouldn't include in a practical piece.
Here are the samples. The red beads are Matsuno (Dynamites), the blue beads are Miyuki, and the silver beads are Toho. The final sample at the right shows all three bead sizes together.
Length: 1 inch/25mm Width: 8mm
Matsuno beads are the most irregular in color, size, and shape of the Japanese manufacturers. It seems like the quality has declined as time has gone by. The beads in this sample were purchased in 2014, and I am very choosy about which braids I use them in because of this. They are also much wider and longer than the Miyuki beads, and the Miyuki beads recede both visually and physically in the sample. To me there is an unacceptable amount of cord showing between the beads.
Length: 1 1/8 inch/27mm Width: 7mm
Toho beads are a bit wider than Miyuki beads, so they match up better with the Matsuno beads. Except where the Matsuno beads are exceptionally wide, there's not much of a difference in width between the two beads. However, the length differences between the two give this a visual irregularity and allow a lot of cord to show.
Length: 7/8 inch/23mm Width: 7mm
This is probably my favorite sample, as the size difference between Miyuki and Toho is very small. It's almost impossible to detect the difference visually, and the slight physical difference is pleasing to the touch. Plus, very little cord shows between the beads.
Length: 1 inch/25mm Width: 8mm
This has a very ridged feel to it, and again there is a lot of cord showing.
In conclusion, I think the Miyuki/Toho pairing is the best one from a visual and physical standpoint. Mixing the three brands in one braid might work in a limited fashion, where Matsuno beads are used in small amounts compared to the others, but I would not recommend mixing Matsuno with Miyuki or Toho beads. Of course , your experiences may be different and I hope you conduct your own experiments to see what you like best.