Pretty much. The fact that you can die, then respawn and come back into the arena and rejoin the fight as long as the party continuously has at least one member in there means that it's going to be really hard for four people to see his health reset. Even with just two of us we benefited from that several times. And like Empty Space said you can second wind more often than not.
I will say that 2 people is a lot easier than 1 person, because while he has a lot more hp he doesn't seem to get any more damaging. So his attention being split means that you often get chances to regen that you wouldn't if you were alone, and only one person has to be running around trying not to die at a time.