Ok. Im going to give my accounts. Its not going to be popular, But it is what it is. Ive tested dozens of different intercoolers now.
Surface area to ambient is of the upmost importance. A thicker core is absolutely not better. It does increase flow and reduce pressure loss. But this is couteracted by further drag and transfer of heat, the further from direct ambient flow the less efficient "as you have qouted". Take a top mount air to air. Thicker is not better at all full stop. As you MUST fit and run a fan. Top mount ATA's dont run anywhere near enough ambient air flow. Unless your intercooler is 12" x 12" and your scoop open surface is 12" x 12" on a vertical plain to ambient air. But thats never going to happen as you wont be able to see the road. It still wont be as good as a front mount as there is an engine in the way adding to heat its trying to dissapate. Which is why a front mount is 100% better. Its 90 degrees to ambient air flow and has a large surface area away from any excessive heat.
The only acception to this "thicker is not better" rule is a WTA. It transfers the heat transfer evenly accross the core no matter what thickness or size. Providing flow and design is correct. It also incorperates a full size radiator thats 90 degrees to ambient with a large surface area. It can cool extremely well with very little pressure drop.
Qouting some intercooler companies is pointless. ASE used to run their front mount upside down hiding it complete behind the bullbar and said it work perfectly with no direct air flow. As it radiates heat. With out ambient flow stripping the heat away, WHY EVEN BOTHER.
Yeah thinner would be better in my case.
So in the end what is a realistic CFM for my engine, are my numbers correct?
W2A would be sweet but it seriously complicated and enlarges the cost about 3-4x what I was anticipating. Plus for all that added cost for a system like AdamBs running 70% you can get that from an A2A if done correctly at a fraction of the cost.
Front mount is not possible for me.
ASE is very overpriced for some Chinese stuff.
ARE cooling on the other hand would be up your alley. They actually post data which you love and ask for. Have a read, they back up their claims with proof just like your testing.