personally i think it's a waste of resources (money, time, etc etc),
i have two 80mm fans blowing on mine (i have five) at the lowest possible rpm and they are inaudible ( tested with every other fan off ), keeping them cool enough,
hence, not worth the effort for more.
agree with Marci, lateral has larger contact area to conduct heat from.
however it would be interesting to see the use of block with a thermal pad, like the koolance :
http://www.koolance.com/shop/product...roducts_id=177
... versus a lateral block.