@Physic: It depends on how they split abilities among classes. People with only 1 class should always be weaker than those that have multiples, but if classes are focused enough they should be self-sufficient. Looking at Gladiator now, it needs abilities from 3-4 other classes in order to be able to tank anywhere within the realm of "effectively", which it is supposed to excel at. If the abilities it gets natively allows it to tank without much trouble, it can instead use the other abilities to focus on self-healing, dealing damage, or other utility stuff/personal playstyle stuff, but you would be able to solely do that one function just by having gladiator.