it works but i didnt notice any particular speed up during game play. upload timing logs seems to stay low but only a few entry is logged so i cant say for sure what's going on later.
btw, i didnt notice any log saying something like "native upload enabled". i first tried new jar without libgdx jars and waited for a crash but that didnt happen. then added jars, set Config.disableNativeBufferCopies to false but i'm not sure if it's actually used. only difference i noticed is, old way continuosly logs uploading times, native one logs a few times.