I didn't actually intend the sizes as requirements -- I was thinking that, for example, applying the half-ogre template couldn't possibly result in a Small creature. If one gave a goblin ogre heritage, for instance, the resulting creature would be Medium-sized. (What with the theoretical availability of Reduce Person charms, I would not say that it was impossible for two creatures of disparate size to produce offspring, so I didn't think of applying size requirements to the templates.)

The potential for abusing these templates does concern me. I don't play with a high-op group, so I'm not too worried about flagrantly min-maxed characters, but it does seem like these are a little too good for LA 0. This is actually one of the reasons I thought I should get some outside thoughts: I was having difficulty coming up with penalties I could logically apply to them -- something that makes sense in-universe, rather than obviously just being there to balance things out. How do you think I might tweak them so that they actually balance between advantages and disadvantages?