At the completion of a project that uses LibRaw, I want to share the more intense algorithm artifact analysis to be helpful for anyone hoping to use LibRaw in the future, and as a thank-you to Alex for the direct support.

To summarize, algorithm (user_qual) 11, DHT, is the best. It's better than the best offered by RawTherapee, too.
Here are the most important examinations I performed!

Fence / Roof comparison:
https://drive.google.com/file/d/0ByFHxc7qU-svVXd6MVEzN0pUajQ/view?usp=sh...

Light comparison:
https://drive.google.com/file/d/0ByFHxc7qU-svQlAwMlZubFJvelk/view?usp=sh...

Cone comparison:
https://drive.google.com/file/d/0ByFHxc7qU-svR2NETGNocWRwUkk/view?usp=sh...

Track line comparison:
https://drive.google.com/file/d/0ByFHxc7qU-svb1ROZXlmWGdTbUE/view?usp=sh...

Black / white checker comparison (animated GIF!):
https://drive.google.com/file/d/0ByFHxc7qU-svUHBPZjUycUxhOGM/view?usp=sh...

Summary table with performance times (on a decently large 16bit image):
https://drive.google.com/file/d/0ByFHxc7qU-svRkVhWGdYTnlOdE0/view?usp=sh...

You can see why DHT is the best choice for image quality, and one of the better choices for speed, but of course nowhere near as fast as bilinear or PPG.

Hope this is helpful!