if you can keep all the welds under the trim line it makes it easier to blend in the repair and hide it.
You need a deft touch and skill to blend it in on a visible part of the panel, which costs money.
But don't take any chances cut out all the rust if you want it to last.
ECP panels can be a bit touch and go for fit, often need a lot of modifying.
Don't be surprised if you have to cut them quite drastically