Trying for an extended period and auditions in the store or at a meet is not the same as living with a headphone and configuring the rest of your audio chain to pair well with a headphone, which is why I would usually try gear that I didn't care for the first time a second or third audition if I didn't use my own gear. It took me a few months with the HD600 to figure out why I sometimes felt fatigued when listen to the HD600 and someone with a lot of experience said that it might be the small peak at 4-5khz of the HD600 that bothered me since brighter headphones like the HD700 and HD800 have peaks that are higher up in frequency and don't fatigue me. Even with this issue I still feel that the HD600 are really great headphones, but they may not be for everyone.To get back on topic, I love the HD600s. I have tried out for extended period of time a number of higher end headphones (HD800S, Ether Flow, Elear, LCD2s) and auditioned a number of others (PS1k, LCD4, LCDX, HD800, Ether) but I honestly think I prefer the HD600s to all of those except the PS1k. I am not going to say the HD600 is an endgame can for me but it plus a PS1k maybe. If nothing else, I think they are the ultimate jazz can.
I still have a number of higher end headphones I'd like to listen to (some Stax setups, HE6, K1000, GS1k and GS2k) so who knows but for me the HD600s are about perfect.
The PS1k is good but I'd never get one since there are better alternatives to me that I've heard and own at 1/4 to 1/5 the price.