How many have actually used these?
Lots

people seem to be having a blast with them, which is great
I think we should see some pics of these babies in action. I am installing some right now and noticed a few things. One, they are pretty cool.
Couldn't agree more
2, they seem to be smaller in diameter than a standard button hole? 3, what are the 2 plastic collars for? One is the nut obviously, but what is the smaller one on top for? Does it go above or below the CP?
Actually the answer to this is all in one. If you look right below the top of the button the plastic has a slightly larger diameter, that fits the standard hole better. If you have smaller diameter holes you can put the collar on top of the control panel and put the button threw a smaller hole. If you have regular hole I put it below so I don't have to tighten the nut down as far.
4, does it matter which tab the 12v is run to, and which tab gets ground? I assume not, but I assumed that with some LED strips once and I was wrong.
This one is pretty simple, if you get it backwards it won't light, you either have to rotate the light or flip the connections. Sorry guys, I am working on AC/DC LED's for pins, but they are a bit more expensive than the bad boys in the buttons
On a side note, I have to take a picture of it, but if you take the pinball machines like TZ or the others with lit buttons on the front, where the button is recessed into the machine, you can elevate a little with the black collar, which I like. Also, the "Start" and "Extra Ball" inserts that are on TZ fit into these exactly! Since TZ is modded all the time, I didn't feel any guilt putting some sweet chrome on the front, I will post pics later.
Thanks for all the support guys it's really fun to see pictures!
On another note...some of the early microswitch holders were out of a more brittle plastic. We have nailed down the right suppliers now and made sure that that plastic is not used anymore. If you have broken holders send us a picture, we can replace them. We had a few break here, but thought it was us being abusive as we didn't hear anything back from customers.