Custom 98, stock (just got a 32 degrees Whisper barrel, but have not used it in a game yet)
Strengths:
Cheap. Mine were said to be fresh, and they had minimal flat spots.
Weaknesses:
Did not seem to break well on impact.
Slimy.
Review:
I have played on two occasions with these balls (probably 1200 rounds total). The last game that I played I hit many players. The balls did not break well on impact. Two people told me that they were hit (hard) several times and even called themselves out despite the paint not breaking. These same people received nice big green splats from my friend's Marballizers. Also, the Menace balls had an oily film on them, although I must admit that I did not notice this until after the game when I was cleaning up. They did not fly very straight, but that may have been partly my barrel's fault.
Conclusion:
Based on my somewhat limited experience with these balls, I would look for something else to use, even if that meant spending a little more money.