You need to look at the K/D vs the main bombers used to hit the strats.
Last tour a 163 had a K/D vs B17s = 3.8/3 = 1.27 K/D vs the other player
vs B24s = 3.6/3 = 1.2 K/D vs the other player
vs Ki67 = 2.7/3 = .93 K/D vs the other player
So the player upping a perk plane has an almost equal chance of losing it before killing all 3 Free bombers in a formation.
The exception looks to be the lancs, but they lack a lot of defense so it does not shock me. They made the choice to carry more bombs to the strat when they took off.
Most 163 pilots really suck. if they don't ram you they spray all over hoping for a hit. Its only the good sticks who already have large perk banks that can make the 163 work so well.