I build a lot of membership sites and permission functionality is a must have. The Agora forum has that and more.
Its easy to use and the developers are on top of any problems in a heart beat.
You can't beat the price either - free right now - It wouldn't bother me if they charged for it though because the support you get is second to none.

Lets face it, after something is installed the only thing left is the support of the product. Go search their forums and you will see the level of support.

Today I posted a couple questions and they were answered within 5 minutes. You can't ask for anything more than that other then they install it for you - which by the way, Hazzaa did just that today too.
I had an earlier version - prerelease version that needed upgrading and it was done for me (don't expect it done for free - their time is worth something as well). I made a donation. Everyone is happy.

They have more Joomla products coming out soon. I can't wait to try them. Knowing their level of skill and commitment to the Agora project I'm sure anything else they create will be just as great.