The MH1 is warmer as you noted, i would pick the MH1 over the 280 any day, the 280 to my ears is flat and boring maybe good for "monotoring" but for pure fun, the Mh1 is better.
Personaly, . i dont like the sound of the 280. worst buy ever... for me. dont even make start with the "Clamp Force of Death", i cant use them for more than half an hour without having a headeach.
The 280's with a Fiio E11 sound pretty fantastic to me. But, oh man do I agree with you on the Clamp Force of Death. I can't wear them for long either.
BTW... can't seem to find the MH1C for 30 bucks anymore on Amazon. Head-fi strikes again?