I'm mildly confused on the relative undervaluing of mainstat in relation to crit hit damage on weapons.
In my mind, with 100% crit chance, ignoring all other stats, 1 mainstat and 1 crit hit damage will add the same amount of damage, scaling more in favor of main stat as crit hit chance decreases.
Is this wrong? Are the formulas for relative DPS skewed in favor of CD for some unexplained reason?
The increase in damage is multiplicative, if you already have 2000 mainstat, one additional mainstat increases your damage not by 1%, but only by 0.05% instead (its still 1% of the base damage). The same would be true for critdamage, assuming 100% critchance, however you simply cannot get your critdamage that high. With the same assumption the optimal damage would be achieved, when critdmg and mainstat are equal, however on a full gearset you can get a lot more mainstat than critdamage, so critdamage is a lot more important to get where you can. This is offset a little by the critchance not being 100%, but is especially true for weapons, the biggest providers for critdamage by far.
Attackspeed, Critdamage, Mainstat and %elemental damage all add multiplicative bonuses to your damage, the more you get from either one, the less effective stacking even more of the same stat gets and the more effective adding more of all the other stats gets. Since mainstat is the easiest to stack up high, all the other stats are usually more effective to raise.
If you're a WD with Gruesome Feast and low crit hit chance, int is much much more effective for your DPS than crit hit damange.
If you're a CMWW wizard with up to maximum crit hit chance and low DPS, crit hit damage will give you an insane damage boost.
I don't think there is a relative formula, but you can load your char into D3up and show "DPS gain by stat". But mainstat rarely trumps ias/cd/cc even if it hits high numbers I checked it for some examples when 1.07 crafting recipes hit and the high int items didn't change much.