What it does:

This is visual replacer, no stats changed. All witcher items can be dyed as normal, except if it's replaced by non-witcher gear. See images for looks and easier understanding.

V4.1
All Griffin armor parts Tier 1-5 (NG&NG+) are replaced by:
- Tier 1 Wolven torso
- Manticore boots
- Tier 3 Wolven gauntlets
- Tier 3 Wolven pants

Assassins gauntlets (crafted) are replaced by Tier 3 Wolven.
Tracker gauntlets (crafted) are replaced by Tier 1 Feline. Additionally, this item now have the same stats as Assassins gauntlets.

V5.1
It's the same as V4.1, plus:
All Feline armor parts Tier 1-5 (NG&NG+) are replaced by:
- Tier 2 Feline torso
- Tier 1 Feline boots
- Tier 1 Feline gauntlets
- Tier 1 Feline pants

V6.1
It's the same as V5.1, plus:
Wolven torso Tier 1-5 replaced by New Moon Armor (i recommend modded look, see below for mod).
Shiadhal's and Ofieri armor replaced by Geralt's white shirt.

V7.1
It's the same as V6.1, plus:
Feline torso Tier 1-5 replaced by Geralt's white shirt.
Ofieri armor returned to normal.

Each version have an alternate one, V4.1a, V5.1a, etc. In those versions Griffin torso Tier 1-5 replaced by Moon Armor and Wolven torso T.1-5 replaced by Wolven torso T.2.
V7.1a is what i use btw.

There's no mention in the books that Geralt used plate armor or chainmail or anything heavier than leather. In the short story "The Eternal Fire" in "Sword of Destiny" he buys a leather jacket.

(My opinion:)
Witchers are made to fight monsters that much faster or bigger&stronger than normal human, and he may be outnumbered. Witcher just cant allow himself to be hit, it'll stagger and make him easier target, he could lose a balance in the middle of a swarm and fall and that's the end of him despite any armor. With large single monsters like cyclop, chort, golem, fiend 1 hit from these can break some bones or knock out. Even if armor will save from that, witcher will lose precious time for recovering which could be used by monster to make another blow and eventually kill. There's a lot of  monsters that can teleport, become invisible, or attack from underground, that's why the witcher must be as quick as possible. Medium or heavy armor is designed for battles in close formation between humans and is not fit for monster slaying. With witchers its all about evasion and attacking, it's like running on razor's edge, no mistakes allowed. Finally, witchers basically live on the road, carriying all that weight from heavy armor is cumbersome even with a horse. Look at Eskel or Lambert, they actually look like witchers.

I dont think that in the Witcher universe there is some ultra-light and indestructable material like mithril from LOTR, yet ingame heavy or medium armor doesnt slow you down at all...

So i changed 3 schools of witcher gear to represent my vision of what is fitting for a witcher. To make Geralt look more lore-friendly without sacrificing combat stats. And to make him look good at the same time.

Changelog:

- Added alternate verison for each replacer
- Glitchiness when wearing Feline pants with Shiadhal's or Ofieri armor is fixed
- Fixed short-emo hair when wearing Tier 5 Feline armor

Installation:

To install extract to "The Witcher 3 Wild Hunt/Mods". Example: "Mods/mod6aGriffinToWolvenV5-1".
Use only 1 version. Run script merger if you arent sure.
Requires B&W, HoS, Wolven Witcher gear DLC.

Made for ver. 1.22, should work on 1.30 or 1.31, needs testing.

To make this i used files from the mod: "Griffin (all versions) replaced with Standard Manticore (no chain mail)"
http://www.nexusmods.com/witcher3/mods/1551/?
And got a permission from mod author monochrony


Modified files (additively):

V4.1
  for Main game&BaW DLC (8x2=16 files):
items\def_item_crafting_armor.xml
items\def_item_crafting_boots.xml
items\def_item_crafting_gloves.xml
items\def_item_crafting_pants.xml
items_plus\def_item_crafting_armor.xml
items_plus\def_item_crafting_boots.xml
items_plus\def_item_crafting_gloves.xml
items_plus\def_item_crafting_pants.xml

  for Wolven gear DLC:
items\dlc10_item_extensions.xml
items_plus\dlc10_item_extensions.xml

V5.1
+ for BaW DLC:
items\bob_item_extensions.xml
items_plus\bob_item_extensions.xml

V7.1
+ for Wolven gear DLC:
items\dlc10_wolf_armor.xml
items_plus\dlc10_wolf_armor.xml

V6.1
+ for HoS DLC:
items\def_item_crafting_armor
items_plus\def_item_crafting_armor

Retextures/remodels should work as intended.

Long Tucked Hair Reworked by Holgar96
GeraltCinematicHair_VanillaColor  - version

Cat Gear Reworked by georgetziotis and CAPA14
Original Witcher sets colors by Scoutbr0
CatReworked + Original Feline Colors

Armor Wolf Extended by CemKey

New Moon Armor - No Dress by Holgar96 (removed for some reason)
^Google drive mirror of this mod
New Face for Ciri V2.0 by Vmars
Ciri outfit better colours and Little Ciri concept art clothes by ziraelxx
Proper Journal Notification Sounds by ralphonzolio
Leave Roach Alone - No More Horse Voice Commands by Valainen
Action Log by Wolfmark
(!) Disable SoftLock Targeting v1.22 by Sunkid
(!) Enhanced Targeting by Mpstark
Razor and Shears (Previously Razor Shaving) by Murzinio
Witcher 3 Witcher Sense Color Customizer by Tomwa Lee Ivory
Stack Your Items by KasparsBITELV
AutoLoot - AutoLoot the items you want by JupiterTheGod
All Quest Objectives On Map by Wolfmark
(!) Absolute Camera by pMarK
Indestructible Items - No More Weapon Degradation by Hemingway
Oils Never Expire by Goat of Death
Toxicity - Clean Face and Screen by DJ_Kovrik
More Quick Slots and Quick Inventory by Wolfmark
(!) Quen Rebalanced by Czartchonn

Cheap dyes everywhere by CorbinDallas
Gremist's Superior Recipes by Gimpypirate
^ Use only 1 of these 2 at the same time.

(!) Instant Sign Casting by xpizdax
If your axii is on "5" then change "IdleTime" to:
IK_5=(Action=CastSignHold,State=Duration,IdleTime=0.1)
to avoid bug that prevents axii puppet from casting

No or Permanent Rune Glow Effect by Gismogin
No RuneGlow No Oil version

Toggleable Cat Potion-Nightvision Effect by jadugarr
no-potion version

Sprinting Tweaks by Zhior
Unlimited sprint everywhere

(!) T.and.M - Threatening and manageable - Enemy scaling mod - Update by KoteBegemote
Fair verison with enemy upscaling on (ingame option)

Enhanced Blizzard Potion by Dominus Sicarum
Relative speed=0%, slowdown 35%, duration 30s, toxicity 15, dont use superior blizzard cause free signs is op

Improved Axii by Fnts
with:
duration.valueMultiplicative = 4.0f;
durationAnimal.valueMultiplicative = 4.0f;
in axiientity.ws

public function GetDamageMod (attacker : CNewNPC) : float
{ return 0.3f;    }
in axiiMods.ws

Rend tweak:
add this in input.settings: IK_Mouse4=(Action=SpecialAttackWithAlternateHeavy)
under categories:
[BASE_ALL_ATTACKS] [BASE_ATTACKS_NO_LIGHT] [BASE_SPECIAL_ATTACK_HEAVY] [Combat] [Exploration]
Change Mouse4 to your preferable key. Equip rend. Try using it as normal attack.