ONI
Amarr Cruiser bonuses (per skill level):
10% bonus to Medium Energy Turret damage
10% bonus to Medium Energy Turret optimal range
Omen
Amarr Cruiser bonuses (per skill level):
10% reduction in Medium Energy Turret activation cost
5% bonus to Medium Energy Turret rate of fire
You lose out on your 40% increased optimal Range and also 40% damage if you’re only at lvl 4 switching to an Omen. Thus making kiting and not being caught much less effective.