Having helped setup and maintain 4 DD bikes, 3x583's and 1x620, over the past 5 years, always fitted plain race chains with soft links, never had one fail. The main thing is the fitting of the soft link, always measure the original link and fit the soft link to measure the same, I have always used a Chain Whale to fit them. Maintenence, is key to the longevity of a plain chain, it Must be lubed after every race, practice, qualy etc, otherwise the pins and rollers will dry out and wear, leading to failure.
Chris
