...I'd be a bit more critical than mike regarding that as some of the seasonic psus would probably hit 86-87% efficiency on 240VA and this Topower based psu barely made it over 80%.
81.3% at 200W output seems like better than "barely over 80%." The curve is fairly flat between 200 & 300W.
The Seasonic S12-430 is the closest match in terms of power & price. This would reach ~85% at 200W w/240VAC. What does that mean in watts? 235W vs 248W measured for the BQ: 13W.
How many people who use 430W PSUs actually reach 200W? HOw often? Not many and not often.
As you said later...
But at low power, I doubt that will make much of a difference, and all other aspects of the psu are positive.
My own main system (P4-2.8G) will pull nearly 200W AC from the wall for a few seconds when I am doing something intensive on Photpshop. Most of the time, it pulls ~95W AC. This P4-2.8 is a Northwood, which is about on par with some of the 89W rated AMD A64s, and mabe a bit higher than the Core 2 duos at idle. The rest -- 1GHz of DRAM, two 7.2k 3.5" HDDs, a fax/modem card, a Matrox p650 dualhead vidcard. The PSU is a Seasonic Super Silencer 350, modded with a Panaflo 80M fan. At 95W AC input, its output is about 70W.
So... let's look at the difference in power draw at 65W load and 240VAC between the S12-430 and the BQ430. Our corrected efficiency test shows the S12 at 83W or 78%. Add 3% for 240VA -- the input should drop to 80W. The BQ was measured at 85W or 76.3.
That's a 5W difference. That's the difference you'll see most of the time for most "quiet" systems run by SPCR readers.
Thermally, energywise -- I think it's really not that big a difference.