Yes, the Centurion case is a poor example of how to build a case with a bottom mounted power supply. When looking at the Antec P180, P182, P190 cases, those cases really show the advantage of properly designed cases with bottom mounted power supplies. A lot of the author's arguments don't hold water with the Antec P series cases.
a) no dust from carpet, since air is drawn from the front
b) no heating of video cards since power supply is in a separate compartment
c) the included "extra" case fans run quietly, so at medium PSU loads, it should run quieter than with just the PSU fan, since at medium loads, two fans rotating SLOWER are usually QUIETER than one fan exhausting the same amount of air. Definitely at low loads when the PSU fan is barely running, the single fan system's going to be quieter.
Plus if you're going to buy that type of case, it would be a wise thing to BUY A POWER SUPPLY SUITED FOR SUCH A CASE! So for the Antec cases that means "old" style power supplies with a fan that sucks out the back and with long power leads... which also means, unfortunately, not inexpensive enough for the budget build, and not super quiet. (My personal choice was an Antec P180 with a PC Power & Cooling Silencer 750 SLI, which still runs at abour $250 retail for the combo.)