Hi,
"Native" acknex's physX plugin uses physX 2.8.5, this plugin uses physX 3.2.2. Internally, physX 3.x is not the same as physX 2.x but I tried to make them look the same when used (similar function names ex pX3ent_settype in ackphysX3 and pXent_settype in ackphysX). There are also many additional things, like better cct, scenequeries (raycast, sweep, overlap) or a different vehicle implementation. I'm working on a better documentation and guide/tutorial.