A best of most worlds system would be to...
  • Trim appearance data from the items themselves. That saves a fair bit of information per item.
  • Introduce a simple 0|1 index --or an expands-as-needed one like Key Items-- for each collected appearance. As soon as you spiritbind a piece of gear, its appearance is collected forever.
  • Move everything in the Glamour Dresser to the above Appearance Collection. Send the stuff therein to the Salvage Collector. The Glamour Dresser's data is no longer required; remove them. This, too, saves a fair bit of requisite information.
  • Appearance and color data is now by-slot and by-job. Changing out one's gear in a given slot has no impact on appearance already set atop said gear via the Glamour Plate. One can still, of course, leave slots empty to then check and inherit the same appearance as indexed by the gear in the given slot.
  • The appearance 0|1 index sources a new Glamour Collection pane, from which one can Try On any and all gear, filterable by whether it's already been collected, by job, by level, etc.
  • Glamour Prisms are used only to adjust n number of slots in a given Glamour Plate.
  • There is one extra "current" plate for each job. You can select however many slots from any given other Glamour Plates to apply to the jobs' held state / current plate.
  • Leveling items the appearances of which differ only in color (such as a brown or green Striking or Scouting set, respectively, with all the same shape, trim, features, and highlights) will be consolidated, simply made immediately dyable (with the expansion-later crafted versions just offering alternate highlights/trims) to save some extra data and accelerate glamour acquisition.

And with that, there's no need to horde items for appearance, reapply glamours as you upgrade a given piece of gear, etc., and one can now mix and match Plates as they like.