i have yet to do it too, my cluster size of my 3ds'es are all 32kb, i plan to backup my content as i am on updated sysNAND ,and have no emuNAND i guess i can just copy my content back in.
@DarkGabbz i only recently found out that 64kb allocation size really does work , but it was for the wii u SD .
i am wondering if it will also be better for my n3ds, maybe loading times will be faster or something..
edit: btw. my laptop which is on win10 , i do not have the option to quick format in 64kb cluster size, i only have that option in easus partition master.
so i guess i will use that after i backup my data someday soon.