I have used them a little, one of our guys has put them to good use.
They cost more, can’t be used in a hopper and have plastic which means they are photodegradable rather than bio degradable. The broken fins are around longer, particularly in the woods, and won’t degrade if trampled into the ground.
They carry their energy for further so some players will think they are firing hot and receive a harder impact.
If you mix standard paintballs with first strike (such as in a combination of hopper and magazine switching as required) then you have to both plan when to switch (if you fire mainly from hopper then there will still be a ball in the breach when you switch over before the magazine feeds a FS, and will feed a FS behind it) and due to their different handling you will have to turn down velocity to ensure they are both within power limits.
Sites and events may have restrictions such as only using them with particular gun types.
However if you put in the effort (time and money) of testing them on the range like our guy, then their fin design gives them a ‘flatter’ flight curve (you may actually find that they still rise and drop in flight)
They give the affect of flying consistently, but suddenly losing energy and dropping
If you know how to use it and put in the practice a crossbow style sight can work well with them
Alternatively you can put the same effort into practicing with quality qpaintballs, fine tune the barrel match and maintenance etc, and if wind is affecting your aim then fire a couple more shots and lead into your target