It's very hard to pinpoint whether doing it had a positive affect. I'm going to say if it did, it was extremely minimal. It's 'nice' for site visitors to see the site is verified I guess.
I'd still do it again, as Google said it's worthwhile. Just a shame it's taken so long, and we couldn't measure success of failure.
I've done it on another site since, which was far smoother, rankings and traffic remained the same though.