Bill since this isn't a private issue is it OK to move from the "Private Pros" forum to the public forum as it could help others and is a good general topic?
But no I've never heard anything about replies being a ranking factor and don't believe it is at all.
However Google DOES like fresh content and now that G+ Local pages are indexed she may 'like' responses.
But like Colan said the main reason to reply should be to acknowledge the customer's compliment or concern, which if done right can make the business owner look responsive and pro-active, which in turn can boost conversions.
New advertising option:
A review of your product or service posted by a Sterling Sky employee. This will also be shared on the Sterling Sky & LSF Twitter accounts, our Facebook group, LinkedIn, and both newsletters.