I just got the ESW9's and it's been some time since I had the K81DJ's, but the AT's are definitely more comfortable. An hour or so was the best I could do on the AKG's but I've been using the AT's at work since getting them and can do multi-hour sessions with no problem. Clamping force is way less than the AKG's.
I'd agree with Blackmore on the amp. Though not bad straight out of my iPhone, these really do well with an amp. And bass is not going to blow you away, but it is in no means lacking. I find them to be much truer to the music than the 81DJ's were.
But like anything else, YMMV!