L700 Mk2 impressions based on less than an hour of ownership:
First of all, the fit is very much improved. The Mk1 had an idiotic design where the top of the earcup couldn't swivel outwards far enough, and it ended up putting too much pressure on the top of the earpad while the bottom wouldn't even seal properly on some people. The Mk2 has a different y-fork, yoke, whatever you want to call it, which is bent inwards and lets the earcups swivel more, and as suspected it creates a better fit. There's still a bit too much pressure on the temples but it's tolerable and at least it seals. And hopefully we'll have no more flimsy plastic pieces breaking. So, it's a step in the right direction.
Those same words can apply to the sound too. The overall tuning seems warmer, tighter, and more focused. I had to EQ the treble down on the Mk1 to make it tolerable, but the Mk2 so far doesn't need it. It's also less diffuse and overly ethereal, more focused and defined, and the bass doesn't have the big midbass bump anymore and is tighter. About the only complaint I have is that the midrange weirdness from the old version is still there, and vocal tonality just sounds off. But a small dip in the EQ around 1.2khz seems to reduce this, so whatever problem is going on seems to be somewhere around 1-1.5khz. The presence region also sounds a bit recessed, kinda like the SR-007 but not to the same extent.
Overall, it's definitely better. Sounds a bit more normal, more like vintage Stax and less like bright, alien modern day Stax - but not totally fixed yet.