Am I right in thinking that all the rules for how armor protects you are unchanged in 1.14 except for allowing multiple protections on the same piece of armor?
And, trying to wrap my mind around how it works, as long as the plain Protection EPF is at least 14 (Level IV + IV + IV + at least II or Level IV + IV + III + III) there is nothing to be gained from a higher specialized EPF (Fire, Projectile or Blast) than 6?
That is Level III or II + I or I + I + I?
(Since the EPF is capped at 20.)
Making low level enchantments less undesirable?
Does this apply to Feather Falling as well?
(Obviously apart from not being able to split it between multiple armor pieces.)
Fire Protection reduces the time you are on fire and this scales with the level, as does the knockback reduction from Blast Protection, while the game only looks at the item with the highest level, so there is no benefit to having more than one piece as long as the EPF is maxed out. Projectile Protection appears to have no other benefits, while Feather Falling II is enough to max out protection from fall damage with full Protection IV (6 EPF + 4 * 4 EPF).
Otherwise, I have no idea if anything has been changed (MCP seems to have died after 1.12 and either way any code that I've found for newer versions has been from examples online since I can't decompile them; I can confirm that the protection enchantment mechanics have been the same since at least 1.6.4 to 1.12); the Wiki seems to indicate not but some testing would be able to confirm (e.g. give yourself armor with +0 armor per piece using commands, so all protection is from enchantments (this also eliminates armor penetration as a variable), and disable natural generation and measure how long you can survive).