Analysis of transformation revamp based on the following thread:
http://vindictushq.com/index.php?/topic/9013-transformation-skills/
Diff between revamped Paladin and Dark Knight:
Trans level 1:
Pally gets +750 DEF, DK gets ATK/MATK +1500 and Balance +4.
Pally gets a party buff that increases everyones SP by 2.5 every 3 seconds for the duration of the transformation. DK gets a party buff that increases everyones max stamina by 150 for the duration of the transformation.
Trans level 2:
Pally gets DEF+750, DK gets ATK/MATK +1500 and Balance +6.
Pally gets Holy Shield, which is a damage absorbtion buff. DK gets Crack of Darkness, an attack where a thorn emerges from the ground dealing AOE damage.
There is no longer a sacrifice ability. It was never implemented in the game and there is now no trace of it.
The extra +10 Balance allows DKs to deal more individual damage than Paladins, as it's highly unlikely that a player can hit 100 balance unbuffed while using a lv 60 weapon. However, as you'll see, that +10 balance may be equalled or exceeded by what the Paladin is capable of depending on the party size and enemy type.
I'm going to assume parties will have at least 1 Pally and DK in it, so the party buffs will be shared. However, if I had to choose, I'd say the Paladin buff is superior as it gives the entire party two full SP meters (8 bars total) over 2 minutes, allowing crazy spamming of SP skills for a lot of total damage. A party missing a paladin trans is missing out on a lot of potential SP, so you'll want paladins just for that reason, if nothing else. Since the buffs don't stack, Paladins could stagger their trans to keep the SP gains going for quite a while in a raid. I imagine a party full of Paladin Evies staggering their transforms for SP gain in order to spam Reverse Gravity could make quite a joke out of even the most difficult raids as the bosses will be more or less perma-stunned. In fact, I wouldn't be surprised at all if the developers reduced the stun/animation time of Reverse Gravity just to deal with this issue.
Holy Shield allows Paladins to absorb quite a lot of damage. This can be used to buffer for mistakes or it can be used strategically to ignore incoming damage and deal some of your own. Just being able to ignore the mechanics of a fight and deal damage where a DK would die may make DKs equal or worse in damage even with the +10 Balance buff to DK. This may be a fight specific issue where some raid bosses deal massive amounts of damage that the holy shield can't cope with, while some 4 man bosses can likely be zerged down while completely ignoring their attacks.
Crack of Darkness is an impressive looking ability, but I'm not sure how much damage it does. Looking at the below video link, the first hit of Crack of Darkness overkills a normal mode gnoll archer for 6204 damage and the second hit takes off a bar of the Veteran Centurial Captain in two hits with some extra overkill. The player probably hasn't put points into buffing Crack of Darkness damage. I'd hope that the move is invincible while active, as your DK is just kind of standing there while it goes off. I'm guessing both Holy Shield and Crack of Darkness can only be activated once per transformation. There's still quite a lot unknown (to me) about these two skills, anyway.
http://blog.naver.com/espelia/127356564
If you plan on soloing a lot, paladin may have the upper hand as you can probably do more damage with the combined holy shield to ignore the fight mechanics and the two SP meters to deal invincible Furious 7, Reverse Grav, or Shield Charge damage than you would with +10 balance and higher max stamina.
Based on these changes, Paladins are for players that need extra protection to make up for getting hit for any number of reasons - mistakes, any kind of lag or stuttering or interruption, etc. The vast majority of Vindictus players fall into this category. DKs are for players that are confident that they won't get hit and that their extra damage can be used to kill the target more quickly. However, the difference is far from clear as the party size and enemy damage can quickly change whether a Paladin or DK will be more effective at killing a target quickly and easily.