I’ve had an MX Ergo for several years (and other thumb trackballs for 28 years), while I like the shape and like the ergonomics, some issues stand out

- Rechargeable battery lasts 4-6 weeks. The 1 AA in the M570 lasted 6-9 months.

- No on device indicator that battery is low or about to die, it just dies mid use.

- Rubberized coating under palm gets guncky over time.

I just bought the only left handed trackball mouse out there and the “huge” from these cats: https://elecomusa.com/

They were a lot cheaper last week. Maybe they have sales a lot or I just got lucky. But I’ve loved them.

MX Ergo is the one I have as well.