Does your company have strict requirements around this type of thing?
Does the decision change if it's for iOS vs. Android?
In short, if you were to build a new SDK today, how hard would you fight to make the SDK open source from day 1?
Integrating with an open-source SDK is one line in Cartfile and a little dragging.
Maintaining one also seems like a hassle, currently all I have to do is tag a release and it just works.