i have a bike with a straight blade carbon fork and one with a straight blade aluminum fork. the carbon fork is very noticeably less "buzzy". j-bends might do other wonderfully magical things to forks as well, but even just comparing like for like (ie. straight blade with straight blade), i like my carbon fork a whole hell of a lot more than my aluminum fork. maybe it's just a design issue and i need to find a better designed aluminum fork, but if i'm replacing my aluminum fork anyway, i might as well just go carbon. i've heard and read a lot of experiences from others about how going with a carbon fork improved the ride of their bike. along with my own experiences, i'm inclined to believe that there might be something to it.