I think its fine as it is, only the cooldown penalty should be lowered a bit after switching between favorites so you dont have to wait that much until you can use them. Not completely to remove because that would make it entirely dumb just lower it a bit.
Now its basically like, you burn all your skills in one go, they set on a individual cooldown depending what are they, switch for another saved favorite, the cooldown starts on that skillset as well. I would be okay halving the cooldown after a switch so you could use that feature more frequently, making the combat even more dynamic, however it would may also make you steamroll the enemy much faster.
Asari Adept and 4 skill slots... that seriously would put the game out of balance. That is, if the 4th skill is another detonator like shockwave. So, a primer (annihilation) and 3 detonators, I would just ditch the sniper rifle all day every day. The current Asari Adept X maxed out is already an amazing character.
