I’ve used both.
EDTracker pro works ok enough for me. My EDtracker pro is from a few years back. Some of my friends have bought it not so long ago, and they’ve had some issues with theirs. I don’t know if it’s because of changes in EDtracker software or something else, such as the surroundings they use it in. I have a car seat in my pit, and I noticed that EDtracker took interference from the metal that was in the headrest, so I had to remove it. I fly WW2 too, where the visibility to my six is sometimes very limited, so I’ve been using the “pseudo 6DOF” (mapping head roll to X axis). It takes a bit of getting used to compared to using Delanclip, that is 6DOF.
I previously had a modded Microsoft VX-1000 webcam, and with that the tracking was not so good. That’s actually the reason why I decided to try EDtracker. A few months ago I started using a modded PS Eye camera, and since had no more issues with tracking. Currently, Delanclip is my 1st option, and I keep EDtracker as a backup for situations where there are interfering light sources behind my back.
I use OpenTrack with both EDtracker and Delanclip.