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...