I bet the 450w model and possibly 500w model are group regulated.
Otherwise Seasonic would use "DC-DC converters!" as a marketing point, noticing how they include "double forward converter design".

Looks like a different internal design.

The lack of OTP and OCP is also disappointing. Every power supply should have OCP on atleast the minor rails. This unit probably uses the same old 8-pin HY-510N protection IC.

At the moment the Corsair CX still looks the better option.
We'll just have to wait some months for reviews.