Have you replaced your shower Glass ?

My shower glass and enclosure are worn out and stained and need to be replaced.

I found 3 companies that will do the work.

One of them claims to have done a lot of them and wants to install the glass like you would in a house with metal framing only where the glass attaches to the walls and the top of the glass 3/8 tempered glass and using clips and silicone on the bottom.  

MY current enclosure has all 3 pieces enclosed in metal, which seems to be more stable.

So my question is has anyone replaced their shower enclosure without using metal framing on all sides of each panel and if yes how did it hold up ?

Here is a pic of what he wants to do.