i don't see any use for the dual casting other than having the ability to use telekinesis to kill merchants with the coins they leave in front of them ...
and then the perks that actually seem useful are blocked by the reduced magicka cost perks which i absolutely don't need due to 100% fortify Alteration and destruction enchants I have (no honestly i can cast mass paralysis after draining my manna to 0 )
also if your wondering how it looked like i was dancing go equip telekinesis in the left hand and detect life in the right hand (your probably gonna need fortify alteration 100% other wise this will drain your manna in like 3 seconds id assume)
now go find a lute and telekinesis it and then as fast as you can use detect life repeatedly (activate and release then activate and release and repeat lots) also it helps to see the dancing if your in 3rd person view