Hi GTR 94,
I think the only way you will get the answer that you are rightly seeking is to do a LOT of research. Try speaking to the distributors ie Advan/ARE/JJ to see how they rate their coolers. Be prepared for a bit of frustration though because it's likely they either won't know or the way they measure wil be different. It's a constant source of amazement that aftermarket suppliers can't provide test results etc for a lot of their big ticket items but people keep buying their stuff so what can you expect? For example some time ago there was a thread on dump pipes - $1800 for CES ones and $1500 for Trust - and no one knows, including the suppliers, what their baseline worth is in terms of performance.
As itbmills wrote, a call to someone like ARE will probably arm you with a whole lot of knowledge regarding how FMIC are rated etc. and it might be best to call them before you speak to anyone else so they know you've done your homework.
Sorry that doesn't answer your question but I think it's the only path likely to yield the info you need. Hope to hear of some good results.
Cheers