Haven't heard either but the M2Tech Hiface got a negative review at Computer Audiophile: http://www.computeraudiophile.com/content/M2Tech-hiFace-Asynchronous-USB-SPDIF-Converter-Review. Interestingly enough, the M2Tech got a positive review at 6Moons.com: http://www.6moons.com/audioreviews/m2tech/hiface.html and EnjoytheMusic.com: http://www.enjoythemusic.com/magazine/equipment/0210/m2tech_hiface_usb.htm.
Ofcourse there is a big differenc in price between these units as well which you need to consider.
Ofcourse there is a big differenc in price between these units as well which you need to consider.