Havoc Demon Hunter Frequently Asked Questions — Shadowlands 9.0.2

At its very base, Fel Rush's damage increase in single target is negligible, and any uptime lost by casting it and moving out of melee range will be very detrimental, and as such is not advised. However, if using Momentum or Unbound Chaos, you are required to cast these to make use of these effects.

Yes. Eye Beam has a bonus damage effect applied to your primary target, which causes it to be worth casting above your other resource spenders at all times. The exception to this is if you expect AoE to occur during the cooldown of Eye Beam, at which point you should consider holding it to gain damage on multiple targets.

The answer to this question in any context will always be to simulate it. This is because what is an upgrade for you may not be an upgrade for someone else. In other words, there is no such thing as a one-size-fits-all answer, even when talking about 2 completely identical comparisons from you to another person. Everything in your gear has an effect on everything else.

This applies to gear, set bonuses, trinkets, and in certain circumstances, talents.

The only exception to this rule is when a specific fight dictates a certain set of optimal talents and gear pieces that enhance their strength. If you are curious about what kind of setup to go for a specific fight, WarcraftLogs.com's rankings and statistics are a good place to see what others are doing.

We have a guide on how to sim yourself here:

For Havoc, there is no strict "amount" or breakpoint of any stat that you are required to reach. Nor are there any points at which a stat stops being desirable. In the majority of cases, the specific secondary you have is less important than the volume. This is however, another case of a situation in which a simulation done to check your ideal gear pieces and stat values will provide you invaluable information.

Due to there only being one choice per faction as a Demon Hunter, there is no choice to be made outside of whether you are Horde or Alliance.