It all comes down to how many modifiers you have to spend for your entire mapping. If you don't need more than 16 than you are good with only two mapping devices (8 mods per each device is available)
You can use software such as CMDR (Windows) or Xtreme Mappings (OS X) to easily merge your devices in to only one or a few more mapping devices. Again, it all depends on how many modifiers are involved.
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