I used the X1 extensively about 10 years ago - timeline included because some other balls have changed factories since then, and there's a chance this might not be relevant.
They were my favourite ball for performance, but durability became a problem when I started hitting with a more advanced group (at the top end, someone who had spent time at an academy and another who used to have a junior world ranking... at the bottom end, me). With the bigger hitters, they were done in a session. These are 4 ball cans and on carpet. I might expect that on acrylic, but on carpet you really expect 2 - 3 reasonable outings. So my impression was that they were great, provided you kept them away from people who have been performance players.