Most professional reviews state that, such as on JonnyGuru. You may see different results as they use expensive/professional equipment. Also, load / voltage regulation isn't the only aspect that determines a PSU's overall performance. For example there is also ripple, transient response, hold up time, etc.
And I'll have to disagree with the S12ii, when the Corsair CX450m/CX550m can be found cheaper. They have better performance, vastly newer platform, and semi modularity. 450w should be enough depending on the rest of your build but 550w is easily enough.
If 450w is enough for your build, and you are willing to spend more towards 400, I suggest the
Seasonic G-450. Better electrical performance and quality than both the Corsair CXM and Seasonic S12ii series.
Corsair CX650m Review (Same internals as CX450m and CX550m).
Seasonic G550 Review (Same internals as G450)