Mixed Tet-Hex mesh or pure Tet mesh?

[assafwei]

Hi,

I was wondering, what is the better practice of these two options:

1. Mixed Tet-Hex mesh (in a complex geometry slice what is possible, mesh with hex, and connect to a conforming tet mesh)
2. Pure tet mesh

Which is preferable? are there any pitfalls in mixed mesh that I have to take notice to?

Thanks.