I have had an Ergodex for a very long time now, but I am pretty new to the Dual-Boxing realm. At this point it is impossible for me to play a game without it.

Pros
1) You can place the keys where you want. If you use your thumb more you can put many keys around your thumb. If you use your index finger or pinky more you can do the same.
- I currently have 8 keys surrounding my thumb position, 6 around my index finger, and 4 around my pinky finger.
2) Ergonomically it is incredible because you can set it up in any position you want.

Cons
1) Believe it or not the keys are very difficult to move if they are close together. So if you want to modify a lot of key positions, your hands are going to hurt from trying to remove the keys.
2) Takes patience to set up.

I have two of them currently and I don't think I could play any game without them.