You can also safe the model directly over Dyne's. I had overwritten accidently the Scorpios model with the one of Tifa once and it worked surprising good. The only problem is that the battle script must be changed for the new animations.
Wait what? I need you to clarify that. Scorpios model is an already playable character, so yes you could switch it with another playable character model fairly easily since they share the same type of **ab file. But if you save a playable character over an enemy then the **ab will be incorrect(Kimera doesn't write **ab files). Since the Playable characters AI info isn't in the scene.bin already you would have to scratch build one for the new battle ID. I guess if you could make a custom **ab file for an enemy player character using Yuffie's as a template to compare between Her playable and enemy **ab files it would be possible. There is a lot of info in the **ab file like animation order etc, and if the number of bones or animations doesn't match the **DA it will crash. Anyway that is the problem with using playable characters as enemies the **ab files are not the same as enemy **ab files. Just switching **ab files might work if the number of bones and animations match, but I haven't seen that done successfully.
I would be excited to see any enemy model that was actually using a playable characters skeleton and animations(other than Yuffie of course). With the animations actually playing in the proper order. Then I could actually use Aerith and Cid for Yuna and Kimahri.