Just thought that I would mention that this DAO “wave” did not wash across all regions of the USA. Houston PD, in Texas, went all-DA/SA in 1997, except that existing duty pistols were grandfathered, if the officer kept up-to-date on quals. There was a huge contingent supporting the Glock system, and their influence finally resulted in the G22 being added to the list of approved duty pistols, a few years later. When the SIG DAK came along, in 2004, there was disagreement, as the rules simply stated that the P229 was an approved pistol, without actually saying that it had to be DA/SA. (Yes, indeed, there were individual officers who embraced DAK, including a contingent of heavy hitters in the specialized divisions, and, a lowly night-shift patrolman named Rex G.) Finally, the policy was amended to specifically allow DAK SIGs.
To drift the thread, just a bit, by 2016, I was able to start carrying a 1911, again, on street patrol, as a primary duty pistol, after attending a transition training class.