S&W should have kept the safety less Shield. And just started selling the factory 9mm barrels again. They would have made a lot more money that way.
Way more people want a factory 9mm barrel for the conversion. Versus people who want a safety less Shield. But also lets keep in mind that if they did that "again". They would lose on the 9mm sales as a complete weapon. More people would just buy the .40 and then buy a 9mm barrel. Thus once again, having both calibers in one weapon.
To each his own, but a safety less design was just a waste of research and development. They could have used more research and development and possibly introduced a Shield in .45 to compete with the XDS. IMO, it was just a marketing gimick from s&w.