henydiah, I think you may have those reversed. To me anyway, it would seem as though the lower wattage cpus don't need a full flat base and 6 8mm heatpipes. Since HDT gives you more efficient dissipation on fewer pipes... supposedly. As in HDT works better on lower heat loads.
Yes you could have all HDT base and have 8 8mm heatpipes like zerotherm ZT-10D but be HDT, but the ones on the edge do almost nothing. They do almost nothing with flat bases, but supposedly even less with HDT. I really like what the polaris does, lots of HDT where it matters and metal shrouds. http://www.performance-pcs.com/catalog/index.php?main_page=product_info&products_id=30407
But honestly, the nearly unanimous king is the silver arrow, which only utilizes 4 8mm heatpipes. Heatpipe quality/orientation/spacing, fin amount/size/density, fans, and base finish all make a difference. From first glance the frio seems like a power heatsink and the more likely better cooler, but clearly the Tuniq Tower does something else right.
So many variables to think about, you really need the reviews to tell you. Most people dismiss the v6 by cooler master as not too great. I bought it before the reviews were out, thinking its design was ingenious with 2 high speed fans which I already planned to use. They use 50 something fins (about the same as other high end air coolers) in a smaller area, more condensed fin arrangement. They also have the V pipe arrangement. The idea being that they have just as much surface area as other high end cpu coolers, but since the fins don't go as high the pipes don't have to travel as far. Also they're is way less fin area not getting any air blown over it (the corners of the fin arrangement where the fan's corners are) so more are gets cooled and the heatpipes get in the way less with V arrangement. The down side is that the fans have to be high cfm and have high pressure to get through the density, and you should have two of them to get the most out of it. I thought for sure the v6 would have reviews that show it being amazing kind of like how it was for hardwarecanucks. Turns out it isn't that great. Good thing I snagged it for $40 with free shipping