Yeah the update just hit today and it's mostly an NG+ thing. I'm still about halfway through my first run and basically upgrading the units I like at +5 to get the Custom Bonus, and everything is going smoothly so far.
Also the game is rather generous with enemies so it's not that rare to get someone to ExC 10. Especially in some stages when you start with 1-2 stranded units and kill a bunch of grunts with counterattacks before reinforcements show up, or when you start using Map Attacks.
I'm loving that when you target somebody it already tells you if it's enough to shoot them down.
Perfect for somebody like me who does a lot of kill distribution management
It's really convenient yeah, I'll probably miss it when I move to V or X after this game since I started here. Just keep in mind that it doesn't account for Critical Hits, so you might get some surprise kills here and there.