Wiz question.

Rk. II slinging Grp focuses Max AA'ed .. Wizard dps vs

Rk. III slinging , Raid focus, Max AA'ed .. Wizard DPS.

Is the difference only 1-2% ? Between both the Rk. II an Rk. III's and the grp focus and the raid focus is only 1-2% ? Or is it much much more ?

Raid is better than group in focus effect, base damage, overall mana pool and mana preservation.

http://www.raidloot.com/Search.aspx?class=Wizard&slot=Arms&text=frostfire&source=TBM

Raid focus 65 -100 (average 82.5)
Group focus 55 - 75 (average 65)

Skyblaze rk II: 31743
Skyblaze rk. III: 33330 (~4% more base damage for ~4% more base mana cost)

So hardly any difference

so base "focus" is +10 % more..

base "Spell dam" is +4% more ..

So does that mean the overall difference between grp geared grp spells max aa'ed wizard, and raid geared , raid spells, max aa'ed wizard is +14% ?

Or no?

No.

The impact of worn focus effects is significantly less than it appears because a significant portion of your damage comes from crits and other modifiers unaffected by focus affects. I'd peg the increase in damage around 4% for a group geared wizard moving to a raid focus (+/- depending on a whole myriad of things) without any ADPS/burn stuff. The more ADPS/modifiers added, the smaller the benefit will be.

The increase to spell base damage going from Rank 2 to 3 is usually about 5%. This is not a pure 5% increase in DPS because some modifiers are a flat addition (e.g. Fury of Kerafyrm adds 1550 crittable damage regardless of your nukes' base damage), but it is fairly close because most of your damage is coming from modifiers (crit damage, focus) that are multiplied by the base damage of your spell.

The biggest difference between raid and group casters is that raid ones should be more aware that they're useless suckpiles anytime their spell gems are visibly ungreyed. So, in theory, they're more conscientious about never seeing that, thus producing about 6x the damage of typical group players.

Based on how many raid guilds are carrying crappy DPS through content, I am not sure this is as true as it was awhile back.

I wouldn't necessarily draw that line at grouper vs raider.