After bearing witness to the ridonkulously-good Swamp Thing machine of 2005, 1293
first used roughtop in 2006 on the center of a 6WD setup. It proved to be the sole highlight of that robot.
I took that knowledge with me over to 1618, where it was really the highlight of
their 2007 machine. (Our driver combined with help from The Algorithm to take it even higher.) The traction proved useful in
2008, especially when we had to
shut down 1629 ourselves.
2009 doesn't count for either 1618's or 2815's robots (the former's last).
Now fully with 2815, and under the leadership of Stephen Kowski,
we kinda went nuts on drive that year--six motors, two speeds, plenty of overkill for the close-quarters driving of 2010 but effective enough for
our collaborator 1398 to win Palmetto. 2011 was a year of restraint,
using "just" four CIMs and wedgetopped kit wheels on a two-banner tear through Peachtree and Palmetto.
So yeah, I'm a fan of roughtop and wedgetop.
We saw the 2012 kit wheels and decided all that wasn't worth going through for the marginal extra traction. No regrets on the move--from climbing the bridges to zipping across the field, we never missed it. It would take a very specific use case for us to go back now. Great job, AndyMark!
Edit: John,
AndyMark claims a CoF of 0.95-1.0. I have no reason to doubt it based off our experience.