Someone else with the same ergonomic setup as me. Model M + Trackman Marble FX is what I've been using since 1999.
I lucked out this last year and ended up with 4-5 more of the Trackmans for free, which is great since I can see
obvious signs of deterioration in the smaller bits of internal plastic on my original one. I've also got at least 2-3 more of the Model M's as backups, courtesy of a local thrift store.
I'm amazed (considering how cheap decent options now are) that so few people pay any attention to ergonomics. Ease of physical interface makes such a difference when you use a computer for 8+ hours a day.
Now if I could just get my display situation under control...