Ended up forgoing the vert. mouse altogether and buying a Logitech MX Master to replace my Logitech G500 (which I've used for many years and is now discontinued) and I'm pretty happy with it so far. I'm even pleased with its gaming performance (probably not OK for highly competitive or pro gamers, but np for me). Mouse was visibly sluggish over Bluetooth but works great over Logitech RF.
Although the MX Master is not billed as an ergonomic device, it fits my hand better than the G500 and I already feel some relief of the slight pain in my right wrist.
I've used a Kinesis Advantage keyboard for about 3 years (and the MS Ergo 4000 for several years before that, in response to pain that developed before I even turned 20) and it's been a godsend. Would like to find a good ergo mouse before I'm forced to.