OK, so since Logitech discontinued the Trackman Marble, I had to come up with another reasonably cheap solution I'm currently using a Kensington Orbit Trackball with a scroll ring (the Logitech had up/down buttons but no ring/dial).
I have to twist the mouse so that my thumb can comfortably actuate the right mouse button (I'm a lefty) but the wrist rest is a separate piece so I can offset the angle of the wrist rest. Of course, then sometimes the wrist rest sticks to my palm when I stop mousing and it ends up on the floor...
Overall, I've adjusted to it, but the Logitech trackman marble was awesome, despite the lack of a scroll wheel, until the buttons started to perform intermittently or when the mouse cord started to short out. I've owned over a dozen of those since the late 90's, and the price at the time ($20-25) was low enough to put up with replacing them occasionally. I could try to replace the micro switches on the Logitech mouse (there's a YouTube video about that) but yeah this time I went with the Kensington instead.
There IS a wireless version of the Kensington Orbit that's ambidextrous, but I prefer wired...
As for the DPI, well it works well enough for me. The wireless version of the Orbit has 400, 800, 1200, and 1600 DPI settings. Mine probably has similar settings but I essentially just dial in the sensitivity and acceleration factor (i.e. small movements slow large movements fast) to my taste.
At $40-50 though, it's a bit more than I like to spend on mice, but there are much more expensive trackballs and not many decent cheaper options these days so yeah... stupid inflation!
The scroll wheel is best described as a bit jerky though... I haven't found a decent setting that can cover a lot of page scrolling when needed but will still creep when you need it to.
So yeah, if your a lefty that hates dragging mice across tables, I'd recommend the Kensington Orbit, but not as highly as I would have recommended the Logitech. The layout of the Logitech trackman marble mouse just works better for me, but I've moved on. There's some Adesso brand that has a similar layout, but the Amazon and Newegg reviews don't speak highly of that mouse so I've avoided it. There's also the Gameball, but that thing is over $100 and I'm pinching my pennies...