I concur as well. I don't detect any manner in which my former theism or my current atheism has shaped, altered, or informed my concept of "ego." I don't know that I have ever had more than an elementary notion of the concept. It isn't something that's come up much, if at all.
I do hold concepts which my atheism has informed, and which are now different from the way I considered them as a theist. But the concept of "ego," specifically, is not one of them. I frankly never gave it any thought, and now that I am doing so, I still see no way in which this concept has altered for me based on my belief in god(s) or the lack thereof.
I would also like to know if theists have some common concept of "ego" that an atheist might not share, as a result of said theism or atheism. And having been a theist and never encountered such, I'd be interested in hearing how one might know this.