A bit late, but I think there won’t be much difference in physics quality when comparing the BGE and Panda3D Bullet. Both use the same Bullet engine unterneath, and both provide a simplified API to the Bullet C++ API (a “facade” if you like). Bullet is primary a game physics engine, and thus trades performance and features for quality. The only difference might be which “tweaking” features of the Bullet C++ engine are exposed at the simplified facade.