So, I've got two mod suggestions for this already epic modpack to get even better: Ars Magica and Mo' Creatures. I'll lay out the ups and downs of each for the convenience of all the readers and especially for the creators.
First, Ars Magica.
Pros:
A completely new way to fight. Since not all people who play Hexxit prefer fighting with the swords and bows created by the Smeltery and Tool Forge, it would allow more players to fight how they want, and would greatly expand the concept of combat to add a range of magic to the options available to fight with.
More enemies. Hexxit seems to have a good focus on combat, as mentioned. Wouldn't it be nice to have a few extra enemies to fight? Elementals, stone golems, mana creepers, and even the Dark Mages, there will be a larger platter of enemies to destroy when out at night, or underground.
More generated structures. Hexxit also seems to encourage exploration. With new mystic mazes and mage towers to explore/conquer/demolish, and loot inside, there's more variety of what there is to see in the dangerous and vast world of Hexxit.
More armor and tools. Although magic-based, there are objects such as spellbooks to hold spells, and mage armor pieces that repair themselves with mana.
Cons:
More GUI. If it matters, anyway, there will be new bits of GUI on the screen showing pieces of information such as how much mana you have, and what casting style you're using. The mana indicator also shows up on the inventory screen.
The story. Ars Magica has a bit of a story of it's own. That could get in the way of how Hexxit is played, but this may also be seen as a good thing to players who like a bit of story, and it can be ignored by those who don't.
And now, Mo' Creatures.
Pros:
Even more enemies. For those who like to live dangerously, more enemies means more enemies. Hexxit's combat focus will be greatly expanded with a larger variety of kill-ables.
More mounts. Whether players like to ride into battle on horseback, or they prefer to do it on a scorpion, there are many more options for moving quickly around a large world. While I personally prefer the chocobo mounts, other players may want more options. In Hexxit, exploration is indeed encouraged, and this expands the range that stationary player bases can strike, while decreasing the time in-between nearer battles.
More friendlies and tame-able animals. When it comes to getting resources, it comes to be a bit slow when trying to get certain things like leather while there is a limited amount of cows, which must be bred to get more cows. There are other animals in Mo' Creatures that drop leather, such as bulls (which are still technically cows). Plus, you can tame some more animals, such as the mouse-catching cat.
Cons:
Requires the GUI API. That more of a technical problem for the creators, as that means Mo' Creatures is actually two mods. Although I haven't checked, it's entirely possible the GUI API is already part of Hexxit.
Other than that, there are no real cons for Mo' Creatures.
Now, I understand the concepts of incompatible mods, and that could be a possibility between Ars Magica or Mo' Creatures and the rest of Hexxit. However, I can tell you that Mo' Creatures and Ars Magica themselves are fully compatible with each other, as they are also with BiblioCraft and Extra Biomes (just ask Paulsoaresjr).
I also understand the concept of copyright and legal matters. While I doubt Ars Magica is actually copyrighted, it still a good idea for the creators of Hexxit to ask the permission of the creators of Ars Magica and Mo' Creatures if you can add their mods to the greatness that is Hexxit.
I sincerely hope the creators of Hexxit will have these mods added. As for the rest of you reading, if you have anything to say about what I've written, or have any pros or cons you think should be added, or want to show your support or rejection of these suggestions, please do so. I'd love to hear what you all think.