Roles / community members as moderators? Aka. Different levels so users?

I've done a bit of searching here (and in the Elgg for Social Networking book - yes I know it's dated) and it seems that there are just 2 roles for users on Elgg: users who have site level access and just plain members.

Does that sound right? I see the Roles plugin by Arck but that is listed as 1.8 only, is that a 2.x viable solution and if so is it still a "install and tinker with" plugin?

I'm wondering about appointing community moderators who can deal with member flagging of content etc but who cannot access any site level controls.