You could add something for a little more oil maybe the Fury when it comes into full availability. I personally would add a blue Vibe in there to have a control ball for the lighter side of medium. We don't know how you have them drilled, but a ball that is not designed to be an all skid flip reaction could be huge if you run in to tougher conditions. I like the Vibe because it is versital and can really smooth patterns out as well as hit like crazy, o and its cheap!
On the four ball roller, I would tell you from experience that they are NOT fun. Loading a bag that has 60lbs of balls, and then all the other stuff on top of it to a total of about 75lbs in an awkward shape into a car/bus if you do the HS bowling is NOT fun. I personally love the 2 ball totes from brunswick, you can get one with a holder for shoes and there are ones without, the tops are clear so you can see what you have in them, they have a nice carry strap and they are a great size to be able to move around. You can get them online pretty cheap or at a proshop for about $50 for the shoe model or about $40 without shoes. They make it real easy to carry every thing. I think they call them Brunswick player totes, I think you would like it better overall but thats me.