I'd like to put my two cents in, but keep in mind this is my first playthrough with the mod on and I've not progressed past Plantera with it on. I only play on Expert, by the way.
As it stands I see no problem with all of the base classes. They're pretty great and seem to last up til the Mechanical Bosses, benefit wise. A couple notes that I'd make is that I think the melee classes should get some form of movement speed/jump height as well as the rogue types. They're going to be moving around a lot more than the others. I've not tinkered with the Rogue or Minion line, so I can't really say for much on them, though.
On the melee tier 3 types, I see very little reason to pick anything but Berserker. I like the idea of Tank, but unfortunately it's not really all that viable as a role in Terraria simply because Damage > Damage Mitigation nearly all times. There's no real way to think about taking hits on a normal basis. Perhaps if the Tank was more of a 'party leader' sort of role? Spitting out tiny Nebula-like spirits that buff whoever picks them up whenever the Tank defeats an enemy, or perhaps when they take damage.
On the Berserker, is there any way to make them actually feel like a Berserker? Perhaps some kind of damage boost based on how much health they've lost. I can see that getting rather broken at higher levels, but at the same time, you try fighting a boss at less than 100HP on expert and not get squished.
The Warrior seems pretty decent, but lacking in flavor really. I don't have much of a suggestion here beyond perhaps some sort of copycat of the Sage but with a Damage Aura instead?
On the Ranged classes, I've seen earlier that you mentioned you were working on them so they're not so restrictive. May I suggest something, then? Both Archer and Gunner fill the same roles just with different weapons, but they're basically the same class. While playing a ranged user in Terraria, you better believe I'm going to have more than just a gun or a bow on me at either time. The other thing is that both guns and arrows act about the same. It's a shame there's not something like 'ranged speed' akin to 'melee speed' because then there'd be a clear shot of Speed vs. Damage that you could base stats off of. And at end game, ammo consumption basically becomes more of an inventory hog than an actual issue. Ranger is pretty good, but perhaps give them the Hunter's Potion effect, and perhaps some other potions like Shine or Spelunker's. Just to fluff them out a little.
On the magic line, I see very little reason to take Sage. This goes in line with the idea of Damage > Defense. Even higher up, in the +30 range, it's still what, a half of a hit more? It could mean life or death, but that's hardly a mage's role. I'd make sage based more on casting MORE, and give them increased mana regeneration and the like, while giving Mystic the classic 'Glass Cannon' approach.
On the Cleric and Saint roles, I notice they don't really get any bonus damage or anything, they're just a walking Ichor Aura, essentially? Perhaps my idea of the Nebula-like spirits can instead come to this class, to truly make them feel 'Support'. Personally I run Thorium which adds a lot of Healer based spells and Radiant Damage for them specifically. I know it's not a good idea to require mods for other mods, but perhaps stick that in there somehow, or add a basic +overall damage just to make them more balanced with the other Tier 3 classes.
That's all I have for now. Also, Ascension Orbs seem far harder to obtain than Boss Orbs, seeing as how Eye of Cthulhu and the like can be made out of pennies for a nearly forced Boss Orb, but you'll have to set up a farm and run your PC overnight if you want to try and take more than two Tier 3 classes. 50 Ascension orbs is too much. Thanks for listening.