Mac,
yeah it's true that clay target shooters are not using single triggers in life threatening situations.
But, olimpic shooters for example are competing for the gold medal and any trigger failure during the comp is going to cost them big time.
These guys shoot a hell of a lot of rounds and IMO there is no way they would want single triggers if there was any reliability issue.

By the way, howz that Merk 470 going?
Did you get a set of dies for it?