I purchased one; it's with my seat en-route to Spencer to work his magic. I had read that Spencer (and a few others) did't recommend the anti-slip for the seating surfaces. I selected black vinyl for the rider's surface much like the stock seat. My wife was willing to take the gamble to help keep her more planted. We selected the carbon fiber pattern vinyl for the sides. Arrived about 10 days after I ordered it.
I took it out of the bag and looked it over when it arrived; looks like it was well made; vinyl quality matches the samples the shipped us for free after we requested them on the website.
I can't fully recommend until I get to see the finished product installed on the seat - but so far so good.