I'm actually a little surprised by the amount of feedback on the DOT knobs. Even though that knob is my personal 2nd favorite after the Tempest one, it is the slowest mover over all the other aluminum knobs by a long shot! The regular and engraved knobs outsell the DOT knob by about 4:1, and the Tempest knob outsells it by closer to 15:1.
On the last couple batches of the Tempest knobs, I've had them tumble deburred to knock off the edges on the knurl prior to the anodizing. That makes them much smoother.
If anyone has played Tempest at
Clay's Ground Kontrol, then you have used my Tempest knob.

Clay had some knobs from my first run, and he told me that after about 2 weeks in the arcade the knurl had smoothed down a bit and it felt very nice, and it is holding up very well in the arcade. It is very common for original Tempest knobs to be wobbly, off-center, and cracked; which is why Clay was interested in something more durable that would keep looking nice for a long time. I think Clay has had my Tempest knob in his arcade for about a year now, and he has been very pleased with it from what I've been told.