What I first noticed with Labuschagne is how open his stance was, as well as how deep in the crease he appeared to be.
Smith is the same way but I feel it is more front-on than open.
On a personal note, my batting did improve with a more front-on stance than side on...something to do with my vision I guess. Cricket is a very "traditional" sport where lot of conventional wisdom goes unchallenged. I took a lot of flak for it but people don't argue against numbers. I tried a lot of different open stances but something inspired by a certain English coach helped me settle on a style. On the pro-scene, it was nice to see someone like Smith change to a "open" stance although people thought he was nuts but his numbers are great. Labuschagne is the same way but he has more reach on the off side, he is a tall guy with long reach. For a short batsman like me, off side can be a problem because I don't have that reach. Naturally, I compensate by moving around in and out of the popping crease.
In the end, whatever works for your body, reflexes, and your vision.