I've never heard of them. They look less conformable than the trackball's moulded fit that, I find quite comfortable, this is not the case I gather?

Whenever I don't use a trackball for any length of time I get wrist pain, so if these are more comfortable then I'm interested in trying one.

Ergonomics is very personal. I rest my palm on the CST trackball so my wrist is in a (near) neutral position and fingers are positioned with easy access to the controls. I manipulate the ball itself with my pointer and two other middle fingers usually with the phalanges proximales part.

thanks, I prefer the trackball using my thumb. I did try one of the logitech ones that you use your fingers with but it didn't really suit me. I'd guess I'd have the same issue with the CST one, though I am curious to try one now, I'll keep an eye out.