Our center put them in about 3 years ago and across the leagues, averages dropped 10-20 pins. The first two years, they were very difficult to fall (bottoms stay flat longer?), a lot of sliding across the deck upright, not a lot of light mixers. I found better carry on my high hits. This year they are falling much easier, with a lot more liveliness and pin action, so averages are up. Most bowlers who know the difference between the Twisters and wood pins here seem to prefer wood only because of the previous few years' experience.