I have to say I was pleasantly surprised. I didn't really have high hopes for the thing after some things I had read.
I haven't hooked it up yet, but it has a lot more rolly action than I thought it would. More rolly action than an Betson/Imperial, but less than a Happ/Atari.
Do note that the white ones ARE NOT the same color white as the Happ or Imperial trackballs. It is only a minor detail that will get on my nerves for a few minutes, but eventually I'll get over it (one side of my cocktail is getting a PS2 2 1/4" Imperial and the other side is an Ultimarc with a Happ's serial interface.
Yes, I'll bet Andy is rolling over in his grave right now (not that he is dead), me ordering one of his trackballs and then hooking it up with the Happ's interface board. Weirdly enough I have never used an Opti-Pac but I have used the Happ interface board like 4 times now, I just keep finding those in cabinets and assorted boxes of parts.
I also picked up his new joystick board at the same time, looks sweet. Now I just need a good excuse to order one of them 49-way boards from GGG.