Since Maya/Mudbox 2012 there is seamless integration between the two programs. As for ZBrush I believe there are plugins that can do this. It may actually be built into ZBrush in newer versions. Been a long time I looked into it. I do remember in the ADP Zak very easily moved between ZBrush and Maya.
In my opinion there really isn't an issue and in that case I would be more concerned about which of the two is more comfortable for you to use.
I have figured out what the internet is. You know what they say about an infinite number of monkeys hitting keys at random on an infinite number of typewriters for an infinite amount of time? Well the internet is like that. There is some big cosmic alien running that experiment here in order to find the answer to some big question or to create the greatest piece of literature known to the universe. From what I have seen so far I am sorry to say they are going to be greatly disappointed.