I went from a Grado Sr-80 to the beyer Dt990 (2010) and I cannot listen to the grados anymore. As far as im concerned, you shouldnt rule out the headphone based on a graph you found online. you never know how its going to sound with your particular setup.
The Dt990 with my millet tube amp rocks. I found myself tapping my toes the other day so i think it has that grado energy with a bigger soundstage. I kept hearing things about how there is too much bass, blah blah blah. Once I got them and tried them I loved them.
Before I had the dt990 i thought the grados were just excellent especially for the types of music I liked. So i am definately a fan of the grado house sound. I dont want to come off as a grado hater here, i love them. In fact I have an SR 225 as well and I feel like the beyers sound is nearly the same as the 225 except there is just more of it.
For me, I suspect the tubes are a good compliment for the beyer sound since it accentuates the mids a little through my amp.
All im saying is, maybe you should give the dt990 a chance instead of writing it off based off a computer chart. maybe they will sound wonderful to your ears too.
Whatever you do, just dive in and enjoy the music. I banged my head against the wall for 3 weeks straight tryign to decide which headphone to get.