I'm not one for long impressions so bare with me. I received the HE1000se on Thursday the 20th of September. They should be burned in by now from listening to music and running pink noise for 72+ hours. I've owned all of the usual TOTL HP's, Sr-009, HD800, HD800s, LCD-4, LCD-4Z, LCD-XC, LCD-i4, Utopia, Abyss Phi CC, and of course Susvara and HE1000v2. Excluding the Phi, which I just received a month ago, v2 was my favorite HP. Susvara was a step up in areas but it wasn't for me due to it's power requirements. At the time I had a Wells Milo Reference amp. It had plenty of power but I found I preferred v2 direct from Blu/DAVE vs Susvara off Milo. Milo is a great amp, but it's a little too warm and the loss of transparency and resolution was not worth the gains Susvara brought to the table. I sold Susvara and Milo right after the SE was announced and placed a deposit on SE. I sold v2's soon after.
The SE's take all that I liked about v2 and improve upon it. It's not a night and day difference, but they are definitely different. They really seem to be a more efficient Susvara. The bass is better controlled with more detail than v2. The sound stage width is reduced from the v2 a bit, but this is a good thing. With the v2 I felt the sound stage was a little too wide at times and imaging suffered. It was hard panned left, hard panned right, or dead center, but it wasn't always a realistic blend from left to right. The SE's image wonderfully. They still have that nice relaxed delivery but the detail is still their in spades. They are very efficient and do well direct from DAVE or Hugo 2 for hotel use (the primary reason I bought them). I ran v2 around -15db direct from DAVE and the SE's around -23db, so ~8db more efficient. I demo gear with various genres but I really only listen to classical/acoustic. Tonally they're very close to v2. I tweak the signature of all of my HP's with Roon's DSP and have found the same settings I used for v2 work well for SE.
I am 100% satisfied with these and can not see parting with them any time soon. Out of the HP's listed I've kept Phi as my primary HP, the SE's and LCDi4. For my needs this list covers all of the bases.