Ok,
I've had more time to think and i've replaced !ismoderator() with $bbuserinfo['usergroupid']!=5 AND $bbuserinfo['usergroupid']!=6 AND $bbuserinfo['usergroupid']!=7
Works fine now and *no* extra queries for this hack

... but I would like to release this as a hack for others and depending on how they have their forum set, this may not always work...
I really would like a way of calling ismoderator once per page view and saving the result as a variable ... anyone know how I can do this? The problem seems to be that the posts are done before the thread code is done ... so I dont know where I can put the ismoderator() line and have it run *once* prior to the posts getting done.