Problem: I've been playing demons for awhile now and whenever list building I have been confronted with the same piece of advise over and over again - fully diversify your unit of Bloodcrushers. I run mostly Tzeentch demons with a unit of Bloodcrushers, a Bloodthirster and Fateweaver as the main punch of the army. In every game where I used the full command I almost never used the icon or never got off a rend. Eventually I dropped it, saved myself the 40pts and invested it in wings for my Demon Prince.

Everyone repeats that advice about wound allocation for demons but I never ever see it readily applied to other armies. Why is it always so pressed upon for the 'crushers yet never used for Space Marines? Instead you see the same wargear choices & upgrades spammed over and over. 40pts is a pretty steep cost to diversify a squad - what I want to know is when does cost, role, and repetition overcome diversification? or do you even consider it when list building?

Example #1: The Stereotype
4x Bloodcrushers w/ Fury, Instrument & Icon > 5x Bloodcrushers

-The full command costs the same as adding another Bloodcrusher to the unit but with wound allocation is thought to be the optimal build for the unit.

Example #2: The Perceived Power Build v. Extra Wound Allocation
10x Crusaders w/ 8 Bolt Pistols & CC's, Meltagun & Powerfist > 8x Crusaders & 2x Neophytes w/ 3 Bolt Pistols & CC's, 3 Bolters, Meltagun, Powerfist, Scout Shotgun & Scout Bolt Pistol & CC

-3 model types within the unit which maximizes the number of attacks in close combat and the number of models benefiting from Accept Any Challenge, No Matter The Odds.
-6 model types within the unit which comes in 12pts cheaper
-Would it be worthwhile to add 2 scouts (shotgun/pistol&cc) to every Crusader squad just to maximize the number of different model types with the unit?

Example #3: Tau?
6x Fire Warriors w/ Pulse Rifles > 6x Fire Warriors w/ Team Leader, 4 Pulse Rifles, 1 Pulse Carbine
3x Fireknife Crisis Suits w/ Team Leader & 2 Gun Drones > 3x Crisis Suits w/ Fireknife Team Leader, Deathrain Suit, Fireknife Suit, Gun Drone, Shield Drone

-For 5 pts we have increased the squad to 3 different model types while only losing 1 pulse rifle.
-While Tau are not wonderful in close combat, effective Tau generals rely on ending close combats during your opponents turn in order to open up enemy squads to a round of shooting. Additional model types help you allocate nasty powerfist and power weapon wounds that go right through battlesuit armor.
-Adjust battlesuit wargear to have a fully diversified unit whenever possible

Final Thoughts: There are a bunch of armies and squads that could really make use of this to help increase their survivability within the game. They often have access to upgrades which cost as little as 5pts or have typical choices which deserve to be seen more. In my short list I found:

-Space Marine Sternguard Squads, Vanguard Squads, Devastator Combat Squads (Las/Missile/Sarge/Bolters), Command Squads
-Space Wolf Thunderwolf Cavalry & Wolf Guard
-Ork Nob Squads
-Fire Warriors, Pathfinders, & Every Battlesuit
-Chaos Space Marine Chosen & Termatinators
-Etc.

It won't save your squad from getting eaten by hammer units, but when faced by tactical squads or other plain jane squads which pack a sarge or equivalent for some added punch it can help keep your own squad alive by stacking power weapon wounds onto one poor guy who gets overkilled. I'm rebuilding my Black Templar this summer and I'm going to give the Neophytes a whirl and see how this goes.