I am personally on the side of not mixing species. My reasons as strictly a hobbyist, are for the ethical implications. I believe nature gave us beautiful animals that have hybridized in the wild, Natural selection has ensured that the only the fittest hybrids survive, and they've thrived. Why mess with it? I try to discourage inexperienced hobbyists from mixing species due to the complications that can be faced and the fact that many hobbyists aren't prepared to deal with these complications. We have to remember that we're dealing with animals and not inanimate objects. We can't throw away an animal because its not perfect, yet some hobbyists would release it leaving nature to do its thing.

Hawaii is over run by non native species of frogs that were introduced by uneducated importers, hobbyists, and others. They weren't aware of the implications of their actions or didn't care. This affects the ecosystem, most times in a negative fashion.

All that being said, I also believe in everyone's right to do whatever they want within the laws. If you feel this is something you need or have a strong desire to do, whether I agree or not is irrelevant. I respect your right to do it.