The link you posted only applies to multi transformer units, aka 1000w and up units. Good try proving me wrong, but their post does not include any design breakdowns of various units and descriptions of where dual transformer and multi rail are different. Having two transformers is the one and only way you can have voltages more than +/-.1v of each other.
Plain and simple rails are nothing more than a safety feature, they do not affect performance. Do not confuse this with multi transformers. Know the product you are buying, read reviews. Even if you don't trust the numbers that are given by the review, learn how the unit was assembled, look at the diagrams, the rail outputs. Example being my OCZ700w. I can tell you which cable is placed on which rail, that way I can evenly load the unit. Ignorance with computers is nothing more than stupidity.
Edit - Pancho
There are many dual transformer power supplies today. Most 1000w and up units are currently dual transformer, as a single cannot handle all of the current.
Example of a triple transformer unit, notice the extremely long case. Currently very very few multi-transformer units can fit inside of the standard ATX psu form factor. I have yet to see or read of one but I'm guessing there is one or two in existance.
The only larger than spec units will be multi-transformer, and even then most are in the form of a single 12v transformer plus a second for the other currents, 3.3v, 5v, -12v, 5vsb, etc.