I have a cyclops but mine has a big rock and so I gave it an ability sort of like the Crusher, and I made the current Troll into something like the Ogre Deathseeker, which I dropped from the army. For me the troll model IS an Ogre, that is mutated by Orc Alchemy to resemble a real Troll (which is much larger) as the troll is size 4 and the ogre deathseeker is size 3. The ogre deathseeker then has the weapons of the troll, which is like saying the same weapons plus a falchion and a net and it has those 'troll like' attacks per action and its cost is adjusted upward.
That way the 'troll' model is not out of place, their is no need for an ogre deathseeker model as it already exists, and I dropped the normal Troll from the army list.
Done and done.
I have a cyclops, some Narneesh from chainmail, a minotaur and I like the idea of adding them as either devout or blackblood. One thing I did though was make them general monsters so when we do a scenerio they can be placed on the board and any faction or army may face them. I have a band of skaven too (a mutant faction of evil dwarves). I could modify that +2 to goblins and instead grant the bonus to skaven too. That'd be a neat little warband and individual.