That's a bit harsh Gino, without even seeing the banner or the art.
I know I will catch hell for this but...Its a banner, jeez.
If it is an exterior banner, I don't see anything wrong with a patch,
always take in account the viewing distance.
No, you won't catch Hell for this, but I don't see it as being harsh, when someone takes the customer out of the equation and makes an executive decision as how to proceed for someone else's business.
The original post was about how to cover up a mistake and if it would properly adhere without coming off, which tells me, he's not ever gonna tell the customer. As people started commenting on replacing it in full, the OP changed his story and things began to go in a different direction from his original question.
Anyway, that was my only point.... at least give the customer the ability to make his own decision, instead of selling a patched sign at full price, regardless of where or how it's gonna be used. I could care less if people patch banners or whatever. We've patched lotsa things, but we always explain it in full to the customer up front and give them options. Everything here pointed to... being evasive.