If you froze a target though, wouldn't the Cryo Explosion have priority over the Biotic one? AP rounds are always a good all-round choice.
Also, Cryo Ammo was great with the Falcon. Even level 1 rounds would freeze groups of mooks in one hit, which you could then detonate.
Yes they would freeze enemies with only Health left, but a Cryo explosion would kill them anyway so no real downside.
Fire or Electric explosions dealt incredibly lower damage than Biotic Explosions. At best, Fire explosions on Armor would deal about the same amount of damage as a Biotic Explosion, minus the AOE stagger, but the problem was that on anything else it was miles away damage-wise. It's hard to beat 6K damage on every situation (Armor, Shield, Health). Electric explosions were crazy bad, not to mention the ammo was the easiest to prime, you could literally decimate the DPS of your allies by transforming their 6K Biotic explosions every 3 seconds into wimpy 200 damage without any possibility to detonate a BE...
Did AP rounds worked with the Acolyte? I don't remember...