How long have you been working with IJ's? Carpets in general?
I've had largely different experiences than you have. Neither of my IJ's have ever attempted to bite...ever. They are my only Morelia that haven't even done it out of a feeding response. I've only kept IJ's for about a year now, so maybe my experience is limited.
As for the rest of the Morelia spilota complex, I would have to say that you have greatly exaggerated and misrepresented their demeanor. While young carpets are usually nippy, they grow out of that phase rather quickly once they realize the keeper isn't a threat. This blanket generalization just does not apply here. I keep Bredl's, IJ's, Coastals, Jungles, and a couple other sub-species, and I can tell you that there is only one Morelia in my entire collection that requires a hook to be handled.
I think an IJ is a great "starter" carpet due to size, ease of maintenance, and.....demeanor. Get a young one so that if it does start out nippy, the 2 of you can grow together, and it won't stay that way.
Hope this helps...anyone out there have a third opinion to add? LOL!
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"He who would stifle debate rather than engage in it, does so at the expense of his integrity and credibility"
Mike Curtin