Fantastic overall cross race tire. I actually prefer these to the higher end Challenge tires. They're easier to mount and more durable. Plus they are designed for a slightly narrowed internal rim width, so when placed on internal rim widths of 20mm+ they plump out to be around 35mm wide - which is a little more comfortable and I think is perfect for my local CX scene.
4 stars because the sidewalls on all the Grifo's I've ever purchased seem to be a little thin and tend to leak a little sealant through the CX season. Not a big deal, but it does mean you need to top off a little more often than other Challenge tires.