For those in this thread who may be interested: waterfall plot of the HD650.
In your plot, you suggested that the HD 600/650 should be the go-to set for beginners, and I have to say I agree - but the question is, whence from there if you like the sound? LCD 2 rev.2 seem like the natural choice, but where else could you go? The HD 650s do have a touch slow bass response compared to a live performance, it's about the only thing that draws me out of the spell (well that and the soundstage, but I'm about to address that...).
Right now, I just got Fidelia working with an AU wrapped VST plugin called Isone that is kinda blowing me away (I've never heard electronic music sound so alive and organically REAL) - but like all HRTF, leaves them from a little to a lot brighter than they might otherwise be. You can EQ it down, but I only need to do that for a few songs. That said, I'd be concerned that the combo would be unusable for any cans that are already treble-heavy.