I don't know about Duuring, but I have played airsoft. And yes, I thought it was awesome. What gets us about combining the two, is the lack of authenticity (as shown by the pictures). Not only are the uniforms just wrong, they're obviously based on Sharpe (which many reenactors consider to be a crime in it's-self). The nock-gun is what really disturbs me. It has no place in a reenactment for several reasons. The biggest of which, being their lack of use by infantrymen. It was originally made for the navy. It also had massive recoil, so I doubt any soldier that didn't pull the arms off of monsters for fun, would have wanted to use it. Another thing is the officer's sword, an 1803 light-infantry sword (curved) would be much more accurate.
So tl;dr, what makes us so hesitant about "airsoft-reenacitng" is the lack of quality and historical accuracy. If they had the same standards as decent "normal" reenactors do, they would be taken a whole lot more seriously.