As maintainer of the exfat-fuse package i found that it does not work anymore on FreeBSD. Problem is that it does not implement create() call, but according to the docs  it should not break anything, because
"If this method is not implemented or under Linux kernel versions earlier than 2.6.15, the mknod() and open() methods will be called instead.". This logic is supported in the Linux, see http://lxr.free-electrons.com/source/fs/fuse/dir.c#L499, but FreeBSD will just return EINVAL. Old pre-10 driver was also working correclty with EXFAT-FUSE, so it is regression cause by new driver. To test it - mount exfat fs and try to create any file, fuse will fail.
Also see https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=199874 for the original description
Is anyone looking at this? It makes using larger capacity USB sticks across OSes pretty impossible as well as large capacity music players.