Playing at v2.5 stable, and willing to even the experience gain among all the troops, I'd find it convenient, that the soldier's stats window, currently displaying the number of past missions and kills, also displays the number of kills in the on-going mission.
Perhaps, it's too much micro-management for some, but still, I do currently take track of these informations with pen and paper, and I'm certain that an automatic feature wouldn't spoil the game interest for me.

What do you think? Is this feature implemented on v2.6?

The screenshot suggests a way to display the requested information on the stats window.
I selected a virgin soldier to recall that the current display is about "past" missions and kills.