What RG is trying to do with their line up is create a similar reaction with stronger or weaker covers, making it easier to transition from ball to ball in their line up. RG is to Storm as Brunswick is to DV8 (Big Cores to Smaller Cores). RG gives the length of Storm without the huge amounts of flip. From what I've seen and thrown, The Low End line has a core similarly shaped to the Spit Fire from Storm. They, pretty much are the same balls as the Star series of balls and roll really well on a wide variety of patterns. The Rumble is going to be a great THS Benchmark for most and that Core is great for the Motion Hole as I have a Shatter with the MoTion Hole. I have loved the Shatter and Wrecker and will have a Rumble by the end of the month with a Motion Hole to compliment the Shatter with Motion Hole. These have been some of the most driller friendly balls ever.
The Disturbed is an Incredible ball for oil (which I have owned and loved). The ball picks up early and rolls heavy, and strikes.... A LOT!!!!! The Deranged is the Pearl Version and rolls equally as good. They are have slightly higher core numbers because the covers are so strong.
Overall, I think the Rumble is going to be another great solid that will be forgotten like the Riot, Horizon Solid, and the Outlaw which strike a lot and because they don't flip. My suggestion, get one or two while you can. For the price and drill versality, you can lose.