Hi Guys,
Dunno if this has been mentioned before, however have just come from xenforo where there is a similar thing to your advanced user tagging. The modification is excellent and well used by out members but wondered if you have ever though of adding user suggestion to it by way of javascript popup? Its something that greatly aids it being used more as it reduces the posibility of someone adding spelling mistakes and when users have difficult usernames to tag it can be hard work to tag them

Originally Posted by Belazor

We're not 100% sure if it's possible to integrate that into the CKEditor, but it's something we plan on investigating at some point in the future

If its possible, I can say from experience its extremely popular with users.