The problem with Hybrid characters
I love the concept of hybrid characters, choosing a mix of skills you want is great fun. But there is one thing that makes some build less fun than they should be: bonuses. Let me illustrate:
Every class meant to be able to do hand combat has a bonus that gives additional 0.8 health per vitality. Demon hunter is not an exception, but the most interesting in terms of hand-to-hand specialization, i.e. Reaver does not have this bonus. So to be competitive you either need to mix it with another close combat class (which can be boring) or be at an disadvantage. For example - Reaver/Shaman gets 40HP per level of Hardiness, while Gladiator/Shaman gets 48. If you play at a high level, e.g. +8 to monster levels it means Gladiator/Shaman is still fun while Reaver/shaman dies so often it is unplayable.
This could be solved by some rebalancing of classes, but since hybrid is about choice I propose allowing the player to choose one more bonus upon character creation. You are still giving up the third skill tree, so this should keep it balanced while allowing many more plausible combinations.