In Move: The user's base must be fully in contact with the surface over which he is moving. On a Ladder you're still declaring Move. Nothing changes this requirement.
Yeah, climbing or using a ladder has been 'batman style' for a long time now. I think since sometime in N2, even...
the more I look into the rules the more I'm getting lost I'm playing infinity since 2012 I never use ladder like this nor play with someone who does (and I'm using ladder every game of infinity ><)
Well, that's only relevant if you decide to stay in the reactive turn in the ladder, when moving all models have efectively 360º vision, plus we have that rule of thumb "if i see you, you see me" (unless MSV2 plus smoke and those special scenarios)
In N2, you could have a climbing+ sniper peek above the roof top, it was not batman style. Same could be done with a ladder. Although the rule that the base must be fully supported did exist. So i guess as you said, sometime in N2 it got clarified that S2 humans and S4 remotes alike all move up batman style. In N3, though, the 'base' in 'The user's base must be fully in contact with the surface over which he is moving', was expended to refer to any part of the silhouette (for base to base contact and other occurrences of the term base) so I guess this cannot be the basis for it anymore. As long as the cylinder is fully supported by the surface, not peaking out, it is technically OK, but So Wrong if we start moving models side way on the ground.
I think it was about a year before N3 that changed so that all troopers moved up walls with their bases flat-to-the-wall. There has been no change to this during N3. The base itself must still be fully in contact with the surface. You're probably thinking of the FAQ diagram that shows troopers on different steps still counting as being in base to base contact.
