I think HD600 does probably sound better than the SRH1540, but they are very close in sound quality. I prefer HD600 sound because it's more tonally balanced - SRH1540 has too much sub bass emphasis to my ears. However, I disagree regarding the treble - I actually feel that SRH1540 has a more laid back and softer treble, while HD600 has more treble emphasis, particularly in the upper octave to my ears, and also more sharpness to the highs.
I agree regarding comfort issues with the SRH1540. Apart from the weird headband design, I also have an issue with the lack of pivoting on the earcups, which makes it quite difficult for me to adjust them proerly on my head. Also, I find that I need to extend the headband quite far, almost to the max, to make them fit well on my head even though my head is about average in size - not large at all.