Personally, I don't think that making any changes to your meta descriptions will change your rankings on Google. It may increase click throughs in the SERPs though, if Google decides to show them.
Do you think that CTR in the organic space has any affect on placement? If so, wouldn't changing your description tag, in a way, change your rankings? It may not be a big factor any more, but I have to think the CTR is in some way used in the algo.