Hi,
I’ve been working with the folks from Mixamo since about April of this year and I think you will find that they are working hard to make their character program Fuse more friendly to UE4. They have a great bunch of folks in the support department (i.e. Chantel Benson, Tyler Georgeson and Matthews) who have provided me with exceptional customer service. Like said, Fuse is a young program. The upcoming 1.3 version should have some more improvements coming so I would highly recommend you stick with Mixamo.