Bullet Physics on iPhone?

I am curious if anyone has tried using Bullet with ofxiPhone?
The Oolong-Engine uses Bullet with the iPhone, but I noticed their-version is cut-down (and modified?) quite a lot from the version found in ofxBulletPhysics.

I imagine some of math/calculations could be pretty heavy for a handheld device, so if anyone has any suggestions or ideas please let me know.