You're done. You've just lost all credibility.

I kid, you're right. They are tools in an administrators belt. To be able to tell your customer you are familiar with an alternative databasing system will show you have a breadth of knowledge which provides more bang for their buck. To be able to understand how an alternative works in order to provide a minimal level of support for a customer's needs, means they are getting more value out of their investment (you). To be familiar enough with alternatives to discuss why they should or should not be pursued will instill confidence in your customer that you know what you're talking about.

You don't have to be an expert but keeping your eyes open and being aware of alternatives is a good thing.