When Yamaha originally released its 2w oil, it was advertised as just being for WaveRunners that had catalytic converters. Overtime, they discovered that this type of motor oil was the best for all WaveRunners. They started to recommend this type of oil for all WaveRunners over their 2s and 2m options, because of its ability to better protect these engines.
My uncle always used to use their 2s oils in his WaveRunners. When he saw the Yamaha 2w oil, he was initially skeptical. Eventually, he decided that he was just going to have to try it for himself. He found no problems after he completely drained the oil from the boats and refilled them with the 2w oil. He liked the way that the new oil produced less smoke as it burned.