The only problem with sandpaper is when people use to much pressure while lapping. Then some of the abrasive grains might become embedded in the hone.
I believe this is what happened to me. My Shapton 16k (as well as my Shapton Pro 12k) left some really nasty scratches. I believe this was due to the lapping with Sandpaper.
It stopped as soon as I started lapping with the DMT 325. I would reinvest in it any time again!

But a lot of guys seem to be fine with sandpaper and their shaptons, so give it a try butif you can afford it, get the DMT 325