1. The DA pull is harder to shoot well compared to SFA/SAO/DAO/whatever. I cannot say that's wrong. All else being equal, having an 8-10# first pull is, from a pure performance standpoint, a disadvantage over having a 3-5# first shot. You can train to overcome it -- both IDPA and USPSA have had multiple national titles won with DA/SA guns -- but it does require proper training and as mentioned previously that training can be hard to find even among otherwise well known instructors.
2. The "DA-to-SA transition" is harder to shoot well compared to SFA/SAO/DAO/whatever. Again, I cannot say that's wrong. In fact, in my experience it's actually the first SA shot, not the DA shot, that tends to be the most trouble for DA/SA shooters and especially for experienced DA/SA shooters. Again, it's not massive nor impossible to overcome, but even a small disadvantage that requires dedicated time to answer is still a disadvantage.
3. Shooter needs to remember to decock. I almost hate to list this because I honestly believe it is 100% the fault of the instructor when it happens, but still in fairness it is a step that SFA/DAO guns do not need.
Now for the pro's:
1. Safety coming out of the holster. A DA/SA gun is always ready to fire as soon as the trigger is pulled with no need to disengage a safety (no need... that doesn't prevent some people from carrying safety-on or being mandated to carry that way). But by dint of a trigger pull that is both longer and heavier than most other actions, there is far more tactile feedback that the trigger is being pulled in between the start of inadvertent unintentional movement and the Big Loud Noise. We've lost sight of this as a community with the prevalence of ever lighter and shorter SFA triggers and candidly I doubt we'll see the pendulum swing back any time soon. Performance on the square range -- particularly by those folks who don't really know how to shoot a DA/SA well -- is real while responding to an unknown assailant in the dark is, for most folks, merely hypothetical. The shooting community always blames the operator for every accident and never considers the role that equipment plays in making some guns more or less likely to facilitate those accidents. So for the most part, I'm barking at the moon on this. I believe it's a huge benefit. When I say it aloud in front of the mirror, there are two of us.
2. Safety going into the holster. While not unique to DA/SA guns, the benefit of having an exposed hammer that can be trapped and controlled during holstering is a significant and demonstrable safety advantage. This is undeniable. I've spent far too much time with far too many departments that have switched from DA/SA guns to SFA guns and seen first hand the result of people who holster too fast with their fingers too close to the trigger, or gear that gets inside the trigger guard, etc. Again, some will argue that it's a training issue and that mistakes are always 100% the operator, but I believe the redundant safety benefit of thumbing the hammer during holstering is huge.
3. DA/SA guns are very shootable with proper instruction and training. As mentioned above, quite a few people have delivered tremendous success with DA/SA guns. While opponents like to harp on the long, heavy first shot they seem to forget about the long string of shorter, light followup shots. Let's compare an average Glock to a typical SIG. The Glock has ~5.5# trigger pull for each shot. The SIG shooter needs to work through a ~9# first shot... and then he's got ~4# trigger pulls until he decocks the gun. With some tuning, the DA pull will still be longer and heavier than the Glock (and thus safer imo) but the SA can easily come down to the 3# range. The first shot is harder, ok. But all the rest are easier.
4. Shooting DA/SA guns trains you to shoot just about any trigger system. I consider this a minor benefit for anyone outside of the professional training realm, but the reality is that if you can master a DA/SA action and maintain your skill level with it, you can pick up just about anything else and shoot it well.
