I'm following my guts that say me big side fan IS the way to cool computer guts. It pushes the air against the whole MB that is a straight forward way to cool everything inside and I do not have to worry about air flow, heat dead corners, separate fans to cool the parts that are not inside air stream. Big side fans make BTX form factor obsolete.The whole air flow theory looks very childish and simplistic (kind of a pool with pipes IN and pipes OUT we have learned time ago in school)
Another rumor my guts deliver that in near future I'll be able to buy big spare fan.