This is one of my two main composite blades, and is the debatably faster one with better feeling for power loops and heavy pushes. I use the blade with Xiom Omega V Asia on both sides. The blades are high quality and come with plastic topsheet coverings that are reusable for the rubber.
This blade has a limba outer ply vs. the Euro which uses Koto. This difference dictates most/all of the differences between the Pro and Euro. I am a limba lover, so I like the Pro a lot. That said, the Euro is the only koto blade that I have ever been able to get along with in all my years of TT so the X-Carbon + Zephyllium must be a pretty good composite all by itself.
The blade is definitely not bouncy and the power really kicks in on harder shots. I used it with T05 with the cell ball in 2014 and having switched to OVA ( Omega V Asia), I don't feel anything is lost with the plastic ball.
The blades are constructed with jointless wood per Xiom advertising to make the blades feel as close to one piece as possible with minimal disjoint. They need sanding as the handle is not smooth and will cause blisters if not sanded. That said, there is a sander that comes with the blade that is sufficient and the labor required is not a lot.
I would not feel that I was using anything inferior to a top Butterfly blade. The issue would be whether you like the handle. The ST handles were very good and felt mainstream. While I currently use the flare, I found it initially not to me suiting but later adapted after I changed my grip recently and my grip change suited the FL handle more than the ST, hence my return to this blade. But I hold the handles closer to the neck and people who like to have the handles in their palm have sometimes complained about the handle being too skinny or the base too fat. It's perfect for me, but I point this out so that you make sure you are comfortable with the handle before purchasing. Handles are a highly underestimated part of blade evaluation.
I will continue to evaluate vs. the Euro over time. Highly recommended, more so because its price point is good vs. quality for similar Butterfly blades if you buy from TT-japan. Initially, its price point was really low, but was raised over time to compete with Butterfly but it is still lower and better, IMO.
Only bad thing ... it is discontinued, so i am looking for a similar blade now.
Going to try the V6 from Friendship, it has a similar composition so i am hoping for the best.