I didn't stop to consider that. But with Incendiary, Cryo and Disruptor Ammo (Soldier Shep), I see no reason to pick any of the Bonus Powers. Really. Drena Rush is your bread and butter, and with the Amplification upgrade, so is Concussive Shot. Max Fitness and Combat Mastery, and voilá, you need nothing else.
Not correct. First of all, even if you don't use any powers besides Adrenaline Rush, you can benefit from Defense Matrix which will grant you 20% damage protection and -15% shield recharge time at the cost of fraction of a second increase in AdR cooldown. Second, you might want to pick Energy Drain to deal with shields, which allows you to stick with Incendiary Ammo — which, with Explosive Burst evolution, can instantly annihilate any non-shielded enemy, especially if you're using a high-ROF weapon. Mitranim
I just realized I challenged an answer instead of addressing the question. Back to the topic. As always, everything depends on your class and playstyle, so there won't be a clear answer. I will address it point by point.
- First of all, both of these powers are redundant because every Shepard has access to squad versions of AP Ammo (APA), Warp Ammo (WA), Incendiary Ammo (IA), and Disruptor Ammo (DA) if your VS is Ashley. While squad versions are weaker, they still can make you reconsider your bonus power.
- APA has low +damage modifiers, and most of its value lies in cover penetration and the ability to "bypass" part of the armor's static -damage modifier. Both are not impressive. Armor can be weakened with abilities like Liara's Warp or WA, which, coupled with a penetration weapon mod, makes APA's bonus redundant. Cover penetration damage seems meager, and again, is redundant in the presence of a penetration mod.
- WA has good +damage modifiers, but lacks anti-shield damage. This means that for maximum effectiveness, you still need an anti-shield ability in your team. This, in turn, makes WA's anti-barrier damage redundant. This leaves you with +health and armor damage, and armor weakening. If you prefer weapons with high rate of fire, WA's +damage modifiers are not high enough to overcome IA's explosive burst damage, even of the squad version. This leaves you with armor weakening. This function can be fulfilled with Warp or Liara's WA.
- Another factor to consider is how +weapon damage modifiers stack. From my observations (I'm not entirely sure about it), ammo powers add a +weapon damage percentage modifier to your damage against certain targets, and it stacks additively with other +weapon damage modifiers from your armor pieces or AdR, not multiplicatively. This means that if you have lots of +weapon damage modifiers from other sources, ammo power percentage modifiers matter less to you. This has two effects: 1) it can make APA more attractive due to best armor and cover penetration; 2) it can make you stick with IA for explosive burst and disregard other ammo powers.
Kudos to anyone who got through this without falling asleep. I hope this information helps, and I remind that I don't pretend all of this to be entirely correct, it's just my observation of the game mechanics. Mitranim
In a typical fight against cerberus troops you have a few mobs with shields, one or two with armor and many without anything. Now you can pause a fight and switch ammo back and forth for each mob you are attacking but that gets old fast, and is a pain you know where. So the key for me is to pick an ammo and just stick with it. For cerberus pick an AP or IA type. Shields drop fast to any fast firing weapon. So a fully auto AR or SMG solves that problem. Now just pick AP or IA based on if you think the armor mobs can be killed with IA over AP. A good option is a fast firing AR with IA and a sniper rifle with AP for the atlas mech after the shields are taken care of.
Unless I am playing a biotic character or have at least two of them in my squad, I always default to IA.Byrdology