Just received a G80-8113LRDUS used. Even without cleaning the caps I can tell they're very smooth, but smooth in a way that's different than the stock Ducky ABS. The ABS caps are smooth in a glassy/icy way, while the POM caps are more of a silky/soft fur type of smooth.
One thing that makes the POM caps textured though, is the laser infilling. You can feel the printing on the caps, which I don't experience on Ducky's stock etched ABS. Might have to look into getting a set of blank POMs to see what they feel like without the infill, but the only set I can find are the $100 sets from Zeal. EDIT: The blank relegendables on the 8113 are smooth af.
All in all, I'd rank the infilled caps a 9/10 in terms of smoothness, the blank ones would probably be are definitely a 10/10.