Yeah I'm wondering the same thing.
I have a MixPre-6 II that has its own timecode... so I was planning on getting a Sync E for my camera.
BUT... if the Track E can do the same things as the Sync E... I might as well get that instead and have a bonus audio recorder for other applications.
The Track E is slightly bigger than the Sync E... but both are still very small. They both have timecode capabilities built-in... and both have 3.5mm jacks (which is how you would jam timecode in/out)
So it's very possible that the Track E can perform as a Sync