This is a cool item. I like the concept, though I think it might just end up turned on 1 mode and it'll just be left there.
My suggestion would be to change some of the values to make toggling it valuable. For example it could be +25% Cooldown Reduction and +50% reload speed or +15 Spirit power and +20% Weapon damage.
One mode you use for gun builds to reload quickly, or for ability builds while your stuff is on CD, and the other mode you use for active combat.