I've brought it up a few times here, but I didn't really get any bites. Unfortunately, console users aren't allowed to post in the main forums over at blizzard.net, which is where a lot of this stuff is discussed in depth.
Anyway, a lot of it is situational. Since you're multiplying a bunch of different factors together, there's no proportional relationship between CHC boosts and stat boosts. However, a good rule of thumb for determining how much your crits contribute to damage is to simply multiply your CHC by your CD. So if you have a 50% CHC and +200% damage, your crits are increasing your base damage by 200% * 50% = 100%. So if your sheet DPS is listed as 100k, it would drop to 50k if your CHC were to magically drop to 0%.
This isn't as complicated as it seems. Losing the CHC boost will drop your Damage ("sheet DPS"), but the HDI will increase your Holy Damage above that now-reduced base. If you use nothing but Holy skills, then it's a simple matter of looking to see whether your Holy Damage listed on your detail sheet, under the description for Holy Damage Increase went up or down.
However, if not all your skills are Holy, then you need to consider the effect that the lost CHC will have on your Damage. Is boosting your primary attack worth it, considering the attending loss to the output of your other skills? That's mostly up to you, and how you balance the use of your various skills. Are you really using Holy 90% of the time, or is it more like 40% of the time, while using Lighting and Fire 30% each? If it's closer to the latter, then sacrificing a bunch of Damage to boost Holy Damage won't be as worth it.
Also, are the skills you're trying to boost actually listed as "X% of weapon damage as Holy"? If not, they don't benefit from the element boost. If you have a 100% CDI, it doesn't extend the range or duration of Frost Nova, but it
will affect the damage done by the Frozen Mist rune.
