While superior to any other home trackballs, they are substantially lower quality than arcade trackballs.
How so?
You have steel rollers (unlike some of the arcade ones), the same bearings as the arcade versions (from what I could tell), and the same ball.
All that leaves are the encoder wheels and optic cards as different from the arcade versions.
Neither of those pieces factors into the equation, as they are not wearing parts.
I used mine for YEARS on my 2600, and it showed absolutely no wear on the rollers when I hacked it, and still spun almost on par with my Happ.
I think Happ uses slightly better bearings than any of its competitors, which would account for the smoothness of them.