@djfluffkins, I'll do my best. :-)
I do not have a great breadth of experience with higher-end headphones, so I can't offer any comparative thoughts on Utopias vs. Ether Flow Cs + ZMF Auteurs; I've not heard either of those. However, that deal with the DAP sounds pretty incredible.
If there's one significant drawback of electrostats, it's lack of portability. In general, you can't because of the energizer, and even if you could you maybe shouldn't because of dust / humidity. Electrostats are great for a quiet, dedicated listening area.
I've taken my Utopias with me on the go with an AK380 DAP (thanks, Massdrop), and that combo is heavenly. It feels game-changing to take a top-end HiFi listening experience out of the house and share it with other people. I probably annoyed a lot of friends and family by subjecting them to impromptu listening sessions and evangelizing about quality audio, but I have thoroughly enjoyed blowing minds and watching reactions. :-)
That said, the Utopias are extremely open and bleed audio both to/from your surroundings. Yes, they're portable, but I wouldn't listen to them on the bus.
If I had to choose between the Utopias and electrostats, well, I wouldn't. To me, they're complementary. The Utopias are, as an overall package, my favorite headphones I've ever listened to. They're a bit heavy, but that's really the only nit worth picking. Sound quality is the real deal; overall presentation is as close to perfect as anything I've ever heard.
I feel that the L700s still have better detail resolution and clarity, but I'd have to dedicate some serious time to A-B them against the Utopias to find good examples of where they're clearly better. What I notice while listening to the Stax is how cleanly every sound fades out into infinity, and how distinctly I can make out every pinpoint source in a track. What I notice while listening to the Utopias is how natural and refined everything sounds.
At the end of the day, comparing the Utopias with electrostats feels a lot like comparing a chef's knife with a santoku. Both can do any job in the kitchen. Each has slight advantages that realistically boil down to nuance and preference. You could be perfectly happy with either. But there's no rule that says you can't have both.
Not sure if that helps or if I've just fueled your indecision further, but that's my take. Everything you've named sounds like a winner. I love the Utopias, I've given a serious look at the L300 limited (which supposedly has the same drivers as my beloved L700s), and I can't stop browsing this discussion because I'm dying to hear the 95X on my Stax energizer.