I'm still replacing switches on my stupid Logitech MX (faulty design that's been going for many years) but once it's dead for good I will switch over to the Ploopy thumb trackball in a heartbeat.
I really like the look of the Ploopy Classic. I use an Elecom Huge, and I love it. I grew up with a Logitech TrackMan Marble (the old school one, not the ambidextrous one) and I loved it. So the Elecom Huge is like a modern version of that old classic, and it's great for office and daily use - not so much for gaming though.