Trackball

I use the Kensington Expert as well. Haven't had a sore wrist since I bought it and it's way faster than a normal mouse - once you get used to it.
 
Logitech M570 here, and it's the best thing ever. My mom's first laptop, back in 1990 or so, had an attachment that snapped onto the right side with a trackball and two mouse buttons. I thought it was brilliant, and then it was a good fifteen years before I ever saw anything of the sort again. I'm really not sure why they aren't more popular.
 
My old trusty Genius Ergo mouse finally gave up a week or two ago, so in the meantime I was using a standard-size black mouse (not for the daw, just web browsing and the like).
I quickly remembered why I got the Ergo mouse in the first place; my hand was in agony, soaring pain after only a few days.

Less than a week ago I purchased a Logitech [ame="http://www.amazon.com/Logitech-910-000806-Trackman-Marble-Mouse/dp/B001F42MKG/ref=pd_bxgy_e_text_z"]Trackman Marble[/ame] (which I'm using right now). Tbh, despite the many positive reviews, I'm not liking the use of the ball all that much. The tracking ball feels quite heavy and protruding; if it had a lower profile and was lighter, perhaps it would be better. I may still just be sore from the standard mouse, though.

Has anyone had both Logitech and Kensington, to compare?

I'm thinking of trying a gamer's mouse like [ame="http://www.amazon.com/gp/product/B00AAQRNQ8/"]this[/ame] instead, with enough programmable buttons that I don't have to reach for the mouse AND an entangling wired keyboard, while having a guitar on my lap as well (which I find really annoying).
Not sure if it would even work with my old Sonar 8, I'm still researching different mouse models.