I have Track's four ball roller, Roto Grips four ball roller, Ebonite fastback four bag inline roller, and two ball totes from Track and Rotogrip. Of them, the Ebonite is nice but I'm over six feet tall and it has a habit of tipping over quite easily, plus the trunk of my car won't close so I have to lay it on it's side. I just never thought it would last very long so later I replaced it with the Track, and then the Roto Grip four baggers. The Track is nice, it's tall, but it doesn't have enough additional pockets in it for my taste. The Roto Grip is shorter in height meaning it hits me on the heal while pulling it once in a while. It comes apart which I suppose makes it easier to get in and out of a car trunk, but I just keep it together. It has enough storage space. I like to carry six bowling balls with me to league...just in case. I've seen a couple of people with six ball rollers but for the most part they also drive pickup trucks or very large SUV's. A four baller with a two ball tote is really more than you need for any league night.
Chuck