I think there are many good points in this thread once again. One thing I can promise, we will offer an alternative to the high-end raiding scene where players don't have to box to win. We will still support boxing but we will also encourage grouping. As other devs and myself already stated this, we would like to create an end-content where players have the ability to chose if they want to box or play solo/duo (but in group set up with other players). If one would decide to chose solo play, we want to offer a solution where they can team up, interact and play social while defeating the top tier content.
So far the best idea seems to be to create instances of the actual top tier, where we'll fine tune content to a 6 player force and enforce 1 client per IP limit to the instance. I personally love this idea.