Hmmm. Just a question but had you issues with caching at any time? Because when I first started with oUF_D3Orbs I tried using wisp m2 models but there was a problem. The model would not show up until it was cached. I'm not sure if that is still the fact though.
The displayId technique fixed that for me because it allowed loading of models that where not cached yet. Imo that was added because Blizzard needed a way to show uncached quest NPC models in the new questframe themselve.
Actually I just found the thread regarding that topic.
http://www.wowinterface.com/forums/s...ad.php?t=34898
Maybe the caching issue only exists when using :SetCreature() and not when calling a model directly via :SetModel().