So, if you add +1 ARM to a Spec ops it costs 5 XP. If you add another two (the next increment) it costs another 5 XP. +3 ARM = 10 XP. OK... but! +3 BTS is 2 XP +6 BTS is 5 XP +9 BTS is 10 XP ...and here's the kicker: Bioimmunity costs 2 XP. Why would anyone ever put points into ARM when +BTS+BioImmunity is so much cheaper (and better)? Oversight? The title reflects CA because those are the only ones I've looked at, but this problem probably appears in any army where Bioimmunity is a choice.