I have one of each. My UDNN is the french soy material and im not overly keen BUT the fit on the nappy is great. I find it slightly more flexible and easy to stuff then a WNNN. I Do also love my WNNN too though
I've not got a UDNN but have three brand new WNNN new style, they are amazing, I love them thiiiiis much! <holds arms wide!> I have mine in bamboo outer, nothing fancy but they look great anyway as they're bamboo towelling so look nice and fluffy. They are very absorbent as well, DD wears them for 12h and has three feeds in them.