I know a lot of folks who love the SERPA, and I have a couple of them in the suitcase on my current teaching tour myself. Many of my students have used them. No prob.
The accidents seem to have stemmed from folks rushing the draw and using the tip of their trigger finger so they could get into the trigger sooner, and doing the latter prematurely. Keep the trigger finger straight and flat until you're coming into the target with immediate intention to fire, and you'll be OK. In other words, activate the release with the FINGERPRINT part of the trigger finger, not the finger TIP.
Other SERPA problems have been rectified. After we discovered it could be torn off the belt in weapon retention training, Blackhawk reinforced that part of its structure. After it was learned that if you were rolling on the ground a tiny pebble could get into the release mechanism and jam it closed, Blackhawk tweaked that part of the design too, and Chuck Buis at Blackhawk assures me that it is squared away now.
The Blackhawk SERPA and the Safariland ALS are both good holsters, and I for one have owned and used both. Choosing between them, two factors stand out. First, determine which of them rides most comfortably and concealably for YOU. Second, habituation may help decide which is the most natural release mechanism for you. If you are accustomed to a thumb-break or the roller mechanism used on Safariland police security holsters, the ALS will have its release mechanism closer to where your thumb is already habituated to reach on the draw. If you are used to working from an open top holster, you may find that the location of the SERPA's trigger finger release is more natural for you.
Best of luck,