We recently rented a vertical tillage machine which was our first experience with this type of equipment.  It did a really nice job preparing the seedbed in one pass; however, I am not sure if they are worth their price tag?  Probably would find a used one if we ever made the investment.  This one has angled gangs like a disc which is supposed to allow more lateral soil movement.  Pulled it with our Deere 8410 @ 8 MPH.