It's just a thought of mine, but I've sat at home and elsewhere with a wide variety of the headphones that Headroom has reviewed and tested, and sometimes their results leads me to puzzlement as well as some of their recommendations.
The HD280 needs to be used frequently. There's the initial sense of disappointment, and as your hearing acclimatises to them as well as the phones being allowed to break in (these must have very stiff diaphragsm to begin with) it does start to loosen out a little. I'll say after three weeks of 'normal' use, you'll start saying 'hey, these aren't bad at all!'. I seem to remember accidentally burning them in over a weekend when I left some stuff running, and I must say that I never really had a problem with the phones but they did change for the better over time. They have a better staging than the DT250-80, less bass that's sure but quite tight and certainly discernible from a decent amp. Portable use means less power so there can be problems, but e.g. the 250 in comparison is very hard to drive from a portable without an amp, so the HD280 certainly gives you more options. One of those 'mini-epiphany moments' I had was with a D-141 and a well broken in HD280, unamped. I liked their comfort and I think they ended up being among the longest-owned of my phones.
It has a tendency to sound rough at times if you've listened to better gear, but still, quite a good general purpose phone with an amp or receiver in my opinion, especially the price they go for.
Having said that I think the Ultrasone HFI-650 is significantly better than both HD280 and DT250-80, although maybe not as good in certain ways as the HD25 and maybe worse in certain ways compared to the K271S. Given my completist fetish, it was certainly odd that I didn't buy them after samping them for the longest period of any other phone at a Head-Fi meet. However a year down the line I'm preparing to cave in.