Haven't heard the PM3 yet, but hear positive things. I can tell you for sure the HE400S will be on the leaderboard. Unless it gets retuned somehow. For $299 it's a no brainer unless you want a HD600/650.
PM3 gets no rebuttal from me, I think it's Oppo's best headphone.
PM-3 is in. Craig likes it. A bit fun bassy, but I think it deserves to be there. Great comfort, great form factor, good price.