Of the options you're presenting, I would prefer #6 (I like #2 as well, but IMO that's unrelated to the topic at hand).
1. Changing initiative in this way would not be something we could easily reflect on the client. Users would have no way to determine at any point in time what their actual Crit Damage Reduction equates to, including whatever buffs/debuffs are present.
2. Some classes have more Initiative on their gear than others, like WH/WE, and this change as-is would completely rebalance those classes. CO and SM have slightly more Initative on their gear than other tanks in T4 (Mythic removed a good deal of WS from Sov since they do more Spirit damage), and this gives them an outright buff. If we wanted to preserve the current balance or make changes, we would likely need to change the itemization for many classes across all tiers. Since items are my thing, I'm not toooo happy with this prospect.
3. Aside from two classes who get +100% crit damage with little tradeoff, there are few if any classes who get bonus crit damage without giving something else up (taking a tactic for example, costs a different tactic that you might have slotted instead). Outside of SO/BW, I don't think the problem is that significant, and those classes can be balanced individually much easier.
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