Poll: Gear progression, horizontal or vertical?

[Sylve]

Prefered playstyle will always effect things tho. For example in wow you could see fire, frost and arcane mages at the same time, even tho perhaps one spec did way more damage then the other 2.

Personal preference is irrelevant to the raiding communities.
Seen any MRDs taking DPS slots in Coil runs?

Also, for the longest time, the only viable raiding spec for Mages was Arcane. Frost was the only viable PvP spec and Fire Mages were laughed at and scorned in ALL content.
Hell, even back in Burning Crusade, you NEVER saw an Arms Warrior outside of PvP, it was Fury or Protection or you got kicked.

If you want to use a Tier 2 set because you 'like' the bonuses over a Tier 3 set with mathematically superior bonuses, you will never see endgame content in your hypothetical scenario. Barring of course your own personal static where everyone involved is more concerned with playing their own way than winning in the most efficient way, like PuGs tend to do.