Going from 120 down to 60 would create a venturi effect. The venturi effect, will increase the air flow velocity and actually drop the temp of the air a bit. The volume would of course be less than running without the adapters, but it would still be significantly higher than a 60 or even an 80 and you get a slight dop in air temp in the process. the only two trade offs see to running a 120 would be as mentioned above, the weight/torque issue (brackets would serve well here especially if you're a lanner and travel with it a lot) and the power consuption as not only is running a 120 more power, it will draw even more when you restrict it. What i do is run a 120 in the case directly above the hsf and just let it stuff air behind the current fan on the heat sink. its a little less noisy than running adapters and still gives a sweet drop in temps. one example is one of my dedicated folders. It has an agoia 1600 @ 1780 and running a zalman flower alone without the fan mod gets me 43*C. after case modding and installing a panaflo 120 mm fan, my temps went down to 38* C and of course case/board temps dropped as well