The main advantage is that it reduces the Runge phenomenon and, hence, it leads to faster convergence rates.

It also presents less numerical dispersion and need less nodes per wavelength (see 1 and 2). So, I would say that you would prefer the method for wave propagation scenarios.

Regarding software that includes SEM, I am aware of the following:

- [FSELib](http://dehesa.freeshell.org/FSELIB/): Matlab software accompanying the book Introduction to Finite and Spectral Element Methods using Matlab.
- [Nektar](www.nektar.info): Spectral/HP FEM open code.
- [RegSEM](http://www.ipgp.fr/~paulcup/RegSEM.html): used for seismic waves mainly.
- [SPECFEM3D](https://geodynamics.org/cig/software/specfem3d/): used for seismic waves mainly.



## References

1. Ainsworth, Mark, and Hafiz Abdul Wajid. "Dispersive and dissipative behavior of the spectral element method." SIAM Journal on Numerical Analysis 47.5 (2009): 3910-3937.


2. Guarín-Zapata, Nicolás, and Juan Gomez. "Evaluation of the spectral finite element method with the theory of phononic crystals." Journal of Computational Acoustics 23.02 (2015): 1550004.