Lots of domains are coming up for renewal and there are better offers than the current registrar. That brings up to the question, if a change in registrar will result in some negative impact of seo of the sites ? How does google with this change ?
You are free to change your registrar. Do not worry about it and go for it. There will be no negative impact. There is no why Google would care about who your domain registrar is. If your DNS records are correct and name servers that hold them are also configured correctly then nothing will change.
I couldn't find a industry heavy weight commenting negatively on the change of registrar. I have done for few sites. Let's see if this has got some effect.