Thanks for clearing that, Nick.
I would certainly think that the Take-System is the fastest way, especially when it comes to rendering and the output of all “Takes”. Which can easily take the Selection Entry. Please have a look at the example:
Scene File
https://www.amazon.com/clouddrive/share/ofWRKwCrlVkuCavjN2FgSdWP2vuEiNv0x9OpCw6tFOO?ref_=cd_ph_share_link_copy
Place all materials, perhaps one extra to the Object. Set all materials to Selection X (or what ever you like) for the Main Take. With each new Child take, drag the material you want for this specific Take and delete the X. Name the Take wisely.
The Layer system is usable, but since the Take system can also handle Layers… To manage Materials only might not work with Layers.
I could think of something with XPresso, but in the end it will be not faster than Layer or Take based ideas, and perhaps more confusing, if the take system is used later on as well.
(BTW, my approach is just a capital X in the Selection field.)
A more manual approach would be, to use Instances, and switch among those.
Scene File
https://www.amazon.com/clouddrive/share/CWa8TcEuwBkkl3L3za60zdaKrFTH2jmP4IduYBIrCHz?ref_=cd_ph_share_link_copy
Let me know if there is anything else, or something that I have missed.
All the best