[Nuttyman54]

As EricH mentioned, 190 used them in 2008 (there were actually two in that design: the large, custom built one for motor power, and a small signal one nested inside for sensor feedback). Having been involved with the design of that robot, and with the coaxial swerve we used on the 2009 robot, I would heavily recommend against a slip-ring swerve for FIRST.

As has been mentioned, slip-rings can be really fussy, but they are also expensive (especially as you get to the size needed to meet motor wire gauge requirements) and have some fairly strict packaging requirements. Most commercial slip-rings are not designed to handle side-loads or heavy impacts, so you're going to end up with a lot of added weight, size and mechanical complexity to get them aligned and well protected. If you need infinite turning, a coaxial mechanical system may seem more complex but in practice is going to be no worse than with slip-rings, and much more robust than modules.

There is also a wealth of information on both coaxial design and modularized designs and programming. If you venture into the slip-ring swerve realm, there's a lot of uncharted waters that is ripe with unresolved issues and untested methods.

tl;dr - Don't do a slip-ring swerve, it's not worth it. If you have to have infinite turning, go coaxial. Otherwise solve it with clever wiring and code, as others have mentioned in the thread.