I wouldn't exactly put much faith in a comparison of PSU units done by PC P&C themselves, as obviously they have a vested interest in ensuring their own units show the best. I'm unsure how you derive that the compared PSU is Antec as the Specs don't correspond to any Antec units I can find.
It would seem to make more sense for PC P&C to compare to the worst generic unit they can find though as naturally they want their own units to look the best in any comparison.
I'm sure if you ask TopPower they can give you documents showing their the best too...
In respect to what temperature the units are rated at, PC P&C generally rated their units at 40C, though they "guarantee them up to 50C operating temp".
Some of their very low end units are rated at 20C.
Enermax rates their units at 25C, except for the NoiseTaker line which is rated at 40C. (unsure what the CoolerGiant series is rated at)
Antec rates their units at 40C.
Fortron rates their units between 25-45C depending on the PSU line in question, they've gone a huge range of PSU's.
Personally, I tend to like Seasonic PSU the most.
I rate Antec up on par with PC P&C in terms of quality, but I generally tend to pass on Antec as their RMA rates tend to be a touch higher then I might like.
PC P&C I'm very high on, but their cost tends to be more then I'd care for and even their so-called 'quiet units' have never struck me as being particularly quiet at all. As their dervived from Zippy/EMac inards they also tend to be a bit later then most manufacturers in corresponding to the latest ATX PSU specs.
I've mixed feelings on Enermax. Their regular units are quite good relative to generic units, but frankly aren't much better then the likes of Thermeltake IMHO. Merely 'Good', but not especially great.
I've quite fond of their NoiseTaker units though, indeed I'm uning one in my current system.
I use Fortron more often then any other manufacturer in the majority of systems I build though, I've a very high opinion of their units.
Most of Fortron's units tend to be rather low of extraneous features though.
Generally I consider the seeming enthusiast obsession with high wattage PSU vastly over-rated though. Even most quality 300-350W units can easily handle loads that you'll find many people on here screaming for 430W+ units for.
Going back to the original question in the thread.
Personally I feel an Antec TruePower is probably the best suited to your quoted specs.
The seperate +3.3/+5V rails will really benefit you tremendously with so many SCSI drives, I wouldn't be too concerned with the +12V rail as your really not drawing an exorbitant amount there relative to many enthusiast systems.
I'd look towards something around a TruePower 430-480 personally, presuming you don't mid the noise of course as the TruePower's aren't especially quiet.