I'm a bit confused by some of the information on the site
I use two (and will grow to three in the next year) ultra wide monitors on a Mac Pro. The monitors currently give me 5260 x 1080. No matter how you work the slow vs. fast settings for mouse, there is always be a need to pick up the mouse to reposition it on the keyboard tray or desk. I see the same issue with the KeyMouse. Eventually, the position of the pointer input device will not jive with the position of the pointer and the surface area.
I see in your FAQ that you didn't plan to produce a trackball version anytime soon, but then I see trackballs in a gallery of progress. I strongly recommend you keep all your pages up to date as I almost decided this was NOT as solution for me, when, with a trackball version, I may be interested.
When using KeyMouse, we have a "Mouse Freeze" feature that will freeze the cursor position while you move the physical KeyMouses back to a comfortable position. This removes the need to pick up the device and re-center, as many do with mice on their mouse pads when they reach the edge. It takes a little time to get used to it, but it works very well, and becomes second nature.
As for trackball, I don't see the conflicting information you mention. As the FAQ states, we are planning to build a trackball version in the future. The Blog shows some of the development that is happening behind the scenes.