I just sold my XR400 and now ride a WR250F. Dirtbike magazine says that the XR takes the rocks, roots, and really ugly 1st and 2nd gear stuff better than the WR. I DISAGREE! I think my WR sucks up the really ugly stuff better. I can get through it faster and get less tired on my WR. Another thing is the seat. Everyone and all the magazines said that the XR seat was the most comfortable thing going. I always got wicked monkey butt. When I bought the WR and felt the seat, I thought it felt like a rock. I though my butt would really get rubbed raw. Well I don't understand it, but my butt just doesn't get half as sore as it did on the XR.
All it did to the WR suspension is adjust the clickers front and rear and I set the sag. As far as the clickers, I just rode through a rocky section, adjusted them, ran through the section again, and repeated until I liked the results.
As far as landing from jumps... I'm a woods guy so my air is pretty small, but the WR definitly lands much better.