I was told that using silicone and mesh in the joints was better than using a thinset and mesh is this true?

That is invalid statement: Yes, you want to use fortified ThinSet and Mesh.

Why is thinset better?

From several reasons:

1. Durarock is cementous product. Therefore, it will bond the best with cementous products, like ThinSet
2. Silicone flexes and never cures "rock-hard". It will create soft, flexible joint that will flex. As result, it will create cracks in grout of your tile wall
3. ThinSet, used for attaching tile to DuraRock, will not stick to Silicone
4. Silicone doesn't stick to cementous products well. Therefore, DuraRock joint will not be well joined together..

Fortified ThisSet is superior product, especially when combined with mesh. Use it. It will serve your purpose well...