Personally I'm more interested in the end result than the certificates.
I specify certified installers only to head off that future day when I try to get something fixed under warranty only to be told that the warranty is void because the installer wasn't qualified/trained/certified to work on that manufacturer's stuff.
As long as it's installed right, works fine, tests okay and I get a full warranty; I really don't care if "Bob the Builder" puts it in.
