In my opinion, without the effect (I mean the fire effect around the head?), it still looks better than having no effect at all, but of course, it's your decision.

Regarding the models in their original format, etc., I honestly don't understand why you think they are particularly valuable. Now, as far as I understand, you can easily run any models in Maya 6 and back. This way, you can at least limit yourself to models from the Heroes games, rather than using a ton of mismatched models pulled from all over the place and downloaded from some random website.