Any downside to using multiple mail and calendar apps on iOS?

I am wondering if there is a downside to using multiple mail and calendar apps on my iOS device? Specifically the iOS devices come with apple provide apps for both, but I have found 3rd party apps that work better for me. If I have both (Apple's app as well as the 3rd party app) configured, am I doubling the amount of data & memory I am using on the iOS device?