These qoutes may not be in order, so I am sorry in advance if they are.
It is indeed one of the better "Bang for the Buck" power supply, especially since 670 Watts is the peak load for that power supply. I own one, its amazing. All rails are within a 3% +/- Tolerence.
It is one of the top two or three.
I don't know for sure, but I doub't "ALL" of them are. I can see a few specific models but I really do doubt all of OCZ branded ones are simply rebadged.
Depends on your price range, among a host of other items to consider, I suggest you take a look at my power supply guide linked within my sig.
FSP doesn't own OCZ, (Maybe FSP Owns a Portion of the company or visversa) you will find that 85 to 90 + Percent of power supplies are rebranded from another company.(This is especially true with the Power supplies on the Avoid List) So While one company may not own another, they may have a different name branded to them after they are constructed. In fact many Brands aren't even made by that company.
To that end it is very wrong to assume that a power supply is good just by its final end user brand that it is given. There are a few examples of Power supplies within well know and respected brands that are not as good as the rest because they are rebadged/rebranded PSU's from a cheaper company. A good example of this is the OCZ Modstream line. Many of those power supplies have fuji capacitors. Which are very cheap. And well, being cheap does not make a good product. You see most good companies have very high quality power supplies, but they may have a specific model made by a cheaper company to cut costs and increase revenue by simply rebadging them as Antec or OCZ even if Antec or OCZ did not make the said power supply.
Sooner or later I or someone else here at Tech-forums will need to redo that power supply guide as information provided within it, along with any other guides is not static and is dependant on the market. So maybe in a year, or five years. Who Knows.