Yeah a log of all the conditions and settings is starting to become a necessity. At least I only have one type of tire setup at the moment. I can only imagine how complicated it gets when you're switching.
The data logging is pretty amazing, but it will be a while until I get into the hang of really using it well. What you see in the Youtube videos is just basic video + gauge overlay, but their software actually does a lot more than that when I'm at my desk analyzing data in it. Again, logs to go with the data would help, so that I can see things like "Hey changing that swaybar setting gains me 5mph at the traction limit in corner X" or whatever the case may be.
You can see a little slideshow about their analysis software here:
Race-Keeper Software | Race-Keeper . Basically, you get graph data for everything that's synced with the track map and video, and you can do side-by-side video + full-data comparisons of laps from different outings or whatever and it syncs those up as well.