[AngryAlpaca]

IMHO it's just this "thinness", not any special design that makes it present less air resistance.

Your opinion is probably wrong. There was a major design change between the two, so you can't just say that the "thinness" is all that changes the resistance.

There's also a thick and a thin BI II - I may have the model names mixed up.

Yeah, they've got entirely different designs.

Well... OK - although I think of the BIP as "one fan" and BI II as "two fan". Make it "two fan" and "four fan" if that's what you're thinking of - not that push/pull makes any sense for silent cooling.

Now you're talking in terms of the BIP and BIP II, rather than in terms of BIX II and BIP II?

They don't seem that badly made - just way too expensive for what they are. My opinion, of course. They certainly don't have the economies of scale that heatercores do. They also don't have the thickness and sub-fin corrugations of heater cores, which, for silent cooling is good design, not bad.

I never said anything about construction.

Hmmm silent - I think we differ on what is "silent". I've tried undervolted-to-silence (~15dB or lower for me) fans on both BIP and BIX rads - and get approximately the same cooling (different systems, but same case model, radiator placement, fan model, motherboard, CPU model, but using CPU diode for hints about CPU temp so only approximately the same - oh and only paying attention to room air / CPU diode delta).

My mistake, not silent, quiet.

I've never used one of these - never even seen one "in the flesh".
And rereading my post - was it the word "preferable"? I should have been clearer - would "preferable in that it's the same cooling at silent fan levels for lower cost" have worked better?

What does the BIM have to do with this? I was confirming paul's statement. It's 103W at 15C difference. It's not the same cooling at any level. It's the same thing as a heater core versus a BIX. A heater core is more restrictive to the air, but it's better built, so it does much better with less air.

More what? More incomplete quotes?
I'm referring to two radiators of the same construction and thickness.
one has about 22 square inches of frontal area, the other has about 45 square inches frontal area. I've said the larger one can shed more heat. What are you going on about? Is this wrong? Would you like to call it BS? You seem to want to do this publicly, so go ahead.

Now we're talking about an entirely different thing!