About raiders. This is something i noticed playing a skill type katar and a melee type.
Here's the thing. For skill type, while hitting a king, i can hit nearly all the hits with little accu, with skills and some melees.
For melee type, i miss quite a number of times with the exact same amount of accu as the skill type.
Skill types are either slower so their chances of getting a "miss" from the game system is significantly lower. So they hit more with lower amount of accu.
Melee type on the other hand hit like 200-300%aspd depending on gears, stacks and so on. They have a higher chance of getting the miss just because they hit super fast. Thus, they need higher amount of accu in order to hit the same class more.
This is raiders.
Btw, if you mention Dual raiders, they already naturally have high accu, high ap, high def (well not really but decent enough), and they are significantly slower than katar raiders or other melee types. So their chance of hitting is even higher than of the skill type katar. Thus hit better.
As for other classes, well i am unsure of this. I have never ever tested any other class in TG besides my raider, and the other classes do fine with about the same amount of accu as all my other pvm types. It might be the speed you're hitting that causes it to have less hits or that the accu simply isn't enough to compensate and counter the crazy dodge that raiders have.
Sorry for going off topic, but just saying what i experienced.