As you may know, it is the practice in Ashkenaz to wear tefillin on chol moed per the Rama, R' Akiva Eiger, the Mishneh Berurah and many others. R' Hamburger spoke about this at the recent Kenes in Bene Brok and noted that by far most Rishonim call for the wearing of tefillin. I'm checking if there's a recording available. I believe someone is putting a package together and is looking for sponsors for the graphics. Let me know if you can help: firstname.lastname@example.org
Here is a writeup on Tefillin on Chol Moed and an audio shiur from Daniel Adler with a German Jewish perspective.