I've only had the 712's for 1 day :)
They are more comfortable than the Lasmex with their big soft pads, but the Lasmex isn't bad.
The Lasmex pads go over my ears but they are a tighter fit and my ears aren't particularly large.
The Lasmex is heavier. All the silver parts, except the silver trim on the cans themselves, are metal.
Sound wise, I've never been much good at describing headphones but I'll say the Lasmex has more bass, but it's not over powering. . maybe soundstage isn't as wide. Listeing to both right now, using a Schiit Modi 2 Uber connected to a Woo Audio WA6, it's hard to say which I prefer. I know I said before that the 712 was better but now I'm not so sure.
I think ZeypherUndellus described them perfectly.
ZeypherUndellusI've only had it for about 2 weeks and there'd be only a couple of hours usage so far. I love it though. It's certainly a step up from the Little Dot and Bravo Audio Ocean, which are both quite decent as well. I'm amazed how much volume the little Bravo puts out. I bought the Sophia Princess tube to go with the WA6 and have never heard it with the Chinese rectifier it came with but apparently it's a decent improvement.