Chipmunk Physics

Hey,

as I'm still in search for the right library to use I would like to hear some opinions about the advantages of 2d simulations in contrast to 3d simulations. I mean would it be reasonable to use a 3d library like ODE, Bullet or newton to simulate 2d problems?
As I found out Bullet has some 2d objects but I never used Bullet so I'm not aware of the possibilities and limits. Is there any difference in accuracy or speed compared to Chipmunk?
Maybe some of you have had the same questions and found an answer?

Using a 3D engine for 2D physics is an absolute pain. It's slow, and you have to do a fair amount of work to continually force the simulation to stay 2D. I tried using ODE for 2D physics for a while and decided it was too painful. It added nothing except unnecessary complexity and workarounds. It was more painful than writing my own physics engine. :p

Yeah thought so.
But the main problem I'm facing right now is to decide to use 2d or 3d. Let's assume you have to model/simulate a pendulum. It's quite possible to simulate a 2d oscillation but what about the third dimension? Couldn't it result in a "total" different motion if you would simulate it 3d?

No. Why would it?

Butterfly-Effect ^^