It really depends on your goal.
For a moving mesh (growing/folding/bending/…) I personally found Toxiclibs to be the easiest library to work with. It seems to me HE_Mesh is not really meant to deal with non-static meshes. Depending on the context you might have to rebuild the whole mesh at each iteration instead of updating a specific set of faces. I would advise asking @wblut on GitHub for a better and more detailed answer.
You could indeed import a separate physics library and apply the desired behaviors/forces to your he_mesh but the conversion between the 2 formats can be costly (ex: convert all the WB_Vertex of a mesh to Vec3D for force computation, then convert back to WB_Vertex for rendering). So, for simple forces like springs, attraction, planarity… you may be better off writing your own functions.
To sum-up: I would suggest Toxiclibs for origami-like folding meshes, and Hemesh for complex static meshes.
Hope that makes sense.