Never had a real one, but wished I did, and a really love the Helix version. Sounds great, and has a bunch of different flavors, especially for not having a rate control.
However, I don't actually understand the 4 button controls. Doesn't matter in a way, just try the different combos, and I like em all, they're just different. Still, I usually have a pretty accurate mental model of what's going on in my gear, physical or not, not so with this.
Doesn't seem like the buttons are straight up additive, in strength or speed, or subtractive, or have any other obvious pattern to how they interact.
Found a manual online for the original Roland version, no help.
Anyone have a clue?