I think it's semantics whether Bonnea was created from a Shadow of a Fallen versus a Fallen. The imprint (Lash) is Lasciel - it's personality, memories, purpose, and some limited version of it's powers are Lasciel's. I doubt Lasciel saw much difference until Dresden changed her avatar. Because that's what Lash was, an avatar of the main being.
In terms of Bonnea's powers and knowledge, I doubt she would be all too different. The biggest difference is that the being Lash had become by the time her and Harry conceived Bonnea, is that Lash was a far more independent being than the original avatar and a far kinder one. So perhaps Bonnea's personality will be less close to Lasciel and closer to the changed Lash. Time will tell.
I get what you're saying Mira about physical. I think a better word is probably visible. Because Bob and Bonnea are not subject much to the laws of physics, rather about as much as ghost Harry. They are far more affected by spiritual laws. Which isn't to say they can't affect the physical world, or that it can't affect them (which gives some hints about the dynamics between the physical and spiritual). We can see their forms however, unlike the wraiths and other incorporeal beings of the Astral Plane. Which is significant, I think.