Small spoiler for Ark of Omen ahead.
So who would benefit the most from this? Knights would do very well. Their troops are essentially dreadnoughts and very strong. I am stil a bit unclear if this work if they are allied in, but I think so. So any army that can ally in 3 ranged armingers probably will. D3 weapons are just to strong.
But who have good troops? With the new detachment many armies can play with no troops at all. On topp of my head
GSC seems to be a big winner. But they are terrible at grind them down, so perhaps behind enemy lines for them.
Custodies also have above average troops. While not bile they can play grind them down quite well.
Ork has good troops, if they get the charge on you. Da jump is good to get things behind enemy lines.
Tyranids are in a rough place, but big blobs of warriors could farm some
CP with grind them down.
Space marines in general did not like their troops before the point drops. But they can arrive by drop pod and I do belive deep strike with some stratagems.
SW in particular can outflank, and they can pack Terminators into units. I am not shure how "horde marine" will play grind them down yet though. There is an argument to push melee units up the field with transports to get behind e emy lines. (Space Wolves in razorbacks?)
What other army has good troops that can be used alongside some of those secondaries? Either good killy troops in an army that can play grind them down. Or very mobile troops in an army that can do behind enemy lines.
Or is this not a good enough incentive to bring troops at all in Ark of Omen?