An added plus is they typically are the modular type from what I've seen and to me makes hiding cables much easier as you only use what you need. I looked at other models after you suggested Cosair, but I found I like the modular ones better.
Also, when I compared the spec sheets, I found the lesser models spec sheet did not list whether the system had over-voltage and over-current protection, under-voltage protection, and short circuit protection. Now, maybe they all do, but if the spec sheet didn't specify it, I move on to the next unit. Now to some that may not be a big deal, but ever since I began using the UPS (after I loss some equipment from brown outs), I noticed that there are lots of power cycling going on throughout the day, so those features were important in my decision.
That is true. Most PSU's are re branded that is correct.
Getting a good PSU is important though, that's one area I don't skimp. Good quality PSU's are more stable on voltage, more energy efficient, and generally run closer to their specs, they are just higher quality and quite frankly, when I have $2000 worth of computer equipment all hooked up to a PSU, I don't see why you would ever skimp.