I'll run HD Multiburst through mine in a day or two. That should show anything going on.
But as I said before, any image processor / enhancer / noise reducer is going to have artifacts. There is no free lunch. One thing I found is with older true 1920x1080i MPEG2 DVHS recordings, the Darbee actually makes them worse. But newer Dish recordings with MPEG4 at 1440x1080, the Darbee helps get them back to 1920 quality. For most BluRays, I shut it off.
The Darbee is just a tool and like most tools, it isn't good for everything. But for the price no serious HT should be without one IMO.