After 2 weeks of living with the 250-ohm and 600-ohm models side by side, I can conclusively say that I like the 250s more. I've mostly been listening to the 600s but they just have too much high end for my likes, plus they have a certain "distance" that I don't like. The 250s have a more pleasant, even spectrum to my ears, and they're just more engaging.
This is all with a V-DAC (with upgraded power supply) and Woo WA3. I suspect other equipment could yield different results.
And now the tough question...............This will be hard to answer, as it is such a subjective question:
How much of a difference is it really?
Would you consider the difference large enough to be a deal breaker, or is it fairly subtle?
I've only compared the 32 Ohm to the 600 Ohm for a short period of time, I felt that the difference was rather insignificant.