Unless your unit is the top, have U ruled out that there is a possibility something might fall from above breaking the glass?

Maintenance of the glass awning will be a challenged over the years in terms of leaking and cleaning.

Imaging if your top unit accidentally dropped something. It may not break the glass but that becomes unsightly. Cigarette butt is so common sight on awnings. Then U may have to disturb the top unit for access to removed it, if is something big.

Also, since is glass, the dirt and stains will be obvious overtime.

And not forgetting that leaking will happen eventually.