I can't back my claims up scientifically, but I've been an avid Edwal 12 user for the past couple of months processing about 50 or so rolls of film in that time span, and it really is a wonderful developer. I'm still getting used to it, though, but I love how it works on my negatives. Printing 9x9" prints from medium format Tri-X 400 I'm having a hard time finding grain in the grain focuser, while maintaining good film speed and soaringly beautiful highlights.
The curve in Don's post reaffirms the look that I like from it with very crisp and brilliant highlights, but not over the top and blocked up. The curve also suggests that you have control by reducing agitation if you don't like the highlights too bright.
I find it most impressive in portrait work, but have found it beneficial in other types of work also.
If Edwal 10 is similar to Edwal 12, but with coarser grain, then you can pick and choose what you like!