The variant with the AT-9 (MTLB ATGM system) is said to have "low visibility" day/night engagement capability. As to what that means literally...
If it has none, at least provides a plausible best guess of the previous variant not having the capability.
Also, speaking of AT6, will it get Top attack capability? The missile by design flies above the target point, and dives at final stage. One of the things that made it desirable over the existing ATGM types.
Dunno if that qualifies as "true" top attack in the Tow-2B sense, since the warhead does not nescesarily hit as close to perpendicular, but its certainly a step up from direct LOS aim/impact point.
Most sources describe this characteristic, but just one from a quick search to post something
http://www.armada.ch/02-6/complete_02-6.pdf Pg 54