I didn't sell mine because it was too hard to drive - but my experience might help.
I started with the 250 ohm Pro. This was back in the days before I had my LD MKIV. Sold the Pro, bought the LD, then purchased the 600ohm 880s. Was very happy with them - either out of my NFB-12 or LD MKIV. More than enough volume and plenty of dynamics. Then I got a chance to evaluate the 600s side by side with a pair of 250s. Differences (if any) were too small between the two - but the 250 could be played straight out of my Studio Anniversary 3 DAP, So I sold the 600's, repurchased the 250's (Premium this time) - and heavn't looked back since.
For pure versatility - I'd go with the 250ohm. You aren't really losing anything sonically IMO.
yea I agree, although the only reason I have a 600 ohm is cuz I found one on sale, with a balanced recable for like $225... I kinda HAD to buy it since it was selling for half of what it cost the owner... that said that's how I wound up with a slew of balanced amps [I own 3 now] and headphones, as my D2k is going to b recabled and re Balanced [for the THIRD time] this week, and the W1000x is shortly to follow in Febuary