Niels,
You "suspect" these are built by HEC? What caused you to think that?
While I see some similarities between these and the Cougar (HEC-built) CMX-series, I see just as many similarities when I compare them to the Enermax Traithlor ECO units. Similarities to both of those series is strange because Fractal hasn't used HEC or Enermax as an OEM previously -- almost all Fractal PSUs are built exclusively by ATNG. (The initial Integra line was built by FSP.)
I guess we won't really know until: Fractal discloses the information, a unit is opened up and dissected, or they show up on the 80plus.org (excuse me... plugloadsolutions.com) website listings.
Oh wait... What's this? Brand new ATNG 450W, 550W, 650W, AND 750W PSU submissions to 80plus.org?
http://www.plugloadsolutions.com/psu_reports/ATNG%20POWER%20CO.,%20LTD_ATM-450%20SERIES-B_450W_ECOS%203942_Report.pdf
http://www.plugloadsolutions.com/psu_reports/ATNG%20POWER%20CO.,%20LTD_ATM-550%20SERIES-B_550W_ECOS%203943_Report.pdf
http://www.plugloadsolutions.com/psu_reports/ATNG%20POWER%20CO.,%20LTD_ATM-650%20SERIES-B_650W_ECOS%203944_Report.pdf
http://www.plugloadsolutions.com/psu_reports/ATNG%20POWER%20CO.,%20LTD_ATA-750%20SERIES-B_750W_ECOS%203945_Report.pdf
Research rocks!