Unity or native library for this iOS app?

Greetings. I'm beginning work on an iPad application that will take live data from a Comet server (specifically Lightstreamer) and use that data to render 3D models on a piece of 3D terrain (built from real-world elevation data and textured with a satellite photo).

Since my 3D requirements aren't super complex -- no built-in animations, no deformation, no physics -- I'm torn between using cocos3d and Unity. Based on my research, it looks like integrating native iOS code with Unity is still a bit of a chore. That's a problem for me as parsing data from the streaming server is heavily streamlined by an iOS library, and I want to use a variety of iOS 5 features as well.

I do realize that the 3D side of the app would probably be much quicker to develop in Unity, if only for the 3D workspace.

Any suggestions would be appreciated from folks who've managed a hybrid project or worked with alternatives to Unity.

Thanks!

/afb