Update to my review on the Reko-X in K3: 

It turns out, they have manufacturing inconsistencies in these discs.  My (previously reviewed) red one's flight plate is slick and tacky, sticks to the hand, with scratches completely covering the perimeter.  I ordered a second K3 in purple, and that one has that expected base plastic matte / fine velvety surface texture.  Releases very well from the hand compared to the red rubber-feel sticky one.  

What's going on at Kastaplast? 

After liking the glow variant as a putter, it just released very well, but is very springy and got too much of a bounce if it landed on the edge of the cage, and it  didn't do good in a headwind for throwing.  So for putting it is, and I bought another, but in K3. 

The K3 feels very rubbery, but not in a flexy kind of way. Just a stiff rubber.  I prefer the chalky feel of base plastics for putting, for a clean predictable release, and this one is just sticky. 

Nevertheless, I ordered another, because nothing putts as well as this.  Now I have 3 total in my putters stack that's getting a little too big. Lol 

 Compared to the Challenger, which was my previous most successful model, the Reko-X has a more aerodynamic shoulder and isn't as deep.  In depth, it's between, say a Pilot or Envy, and the Challenger.  I'd say it's an improved Challenger, for putting. 

Thumbs up for the Reko-X, thumbs down for K3. 

I wish they offered a better-feel base plastic that's not hard. 

I use reko x's as my putting putters and I absolutely love them. The have a pretty big bead which I love. Pretty close feel to putting with a midrange but that's exactly what I wanted. As a throwing putter they are pretty straight with a reliable hyzer finish. They can handle a lot of torque but I do not throw them that often.

I'm going to put a disclaimer first for folks who like the original Reko, the Reko X is an entirely different disc.

The Reko X is an excellent slightly overstable putter. It fills the space nicely between an approach disc, Zone, Harp, Toro and a neutral putter. I would compare the spot it fills similarly to a Prodiscus Jokeri, Discmania Sky God or maybe even an Aviar x3. It has just enough torque resistance that unless you juice it it will stay nice and straight and fade gently out. Personally I like beaded putters and I find this to be just as comfortable putting as well as throwing. I also recommend the K3 Glow plastic. Had solid stability and the plastic is very grabby.