I did the same search but I don't want to wade through pages of argument and finger pointing, I was hoping someone had a link to reports by the actual users.
I am aware of the incidents. You will find that there are happenings of this sort with all of the models out there given enough units on the market for long enough to measure the incidents.
Please understand that many rebreathers on the market have been around for long enough that the same model has undergone changes over time. So, there are reports that may concern older versions that would no longer apply to newer versions. Let me speak of the Hammerhead in particular since that is a unit that I use and know intimately.
Much older versions of the Hammerheads were in an acrylic housing. These become problematic on very deep dives due to the material flexing. Newer models (since about 2005) are made from different materials. These issues of the acrylic sets no longer apply.
The first aluminum housing sets, which came out in 2005, were nickel plated. They looked really slick, and they worked well in fresh water. Unfortunately, the nickel plating application was not always done properly. In fact, it was much more often done improperly. Once taken into salt water, the case would tarnish rapidly. The manufacturer changed the design to an annodized aluminum housing in 2006. No more tarnishing problem.
In both aluminum sets, the nickel and the annodized versions, there were some problems on some units with the battery contact not being sufficient with the spring. (Other units on the market have had similar problems, i.e., VR3, Shearwater and others.) This required some minor maintenance to the battery cases occasionally. (On my unit, though I never had this problem, I performed a simple contact cleaning about every 10 to 15 hours. This was very simple to do.) There are many people still using the aluminum sets without any problems. They just require a little bit of work to maintain.
The newest version are made from delrin. These were launched in 2007. The sets are smaller and lighter than the aluminum sets. The battery compartment and spring are made differently, and this has resolved this problem of the aluminum sets. These sets have turned out to be extremely reliable. However, there is no such thing as perfection with any component that is produced. So, there will still be the occasional failure. If you were to remove all prior sets from the list of failed units, the delrins would have a very low failure rate.
You will find that rebreather components are undergoing rapid transformations and improvements. These happen as more units are on the market, and as the manufacturers get more feedback from users. So, there will continue to be upgrades and changes to models as these improvements come to market. (Heck, even regulators often come out with changes and improvements from year to year eventhough this technology has been around for 50 years.) If you are waiting for the
final design version of a rebreather to come to market so that you can buy one at that time, you will be waiting probably forever for this to happen. So, be prepared to deal with the nature of the industry if you are going to consider purchasing a rebreather.
Meanwhile, there is a reason that rebreathers come with redundant components. Since there are occasional failures (everything will eventually break on all equipment), having redundancy takes care of the occasional break down. With a diligent diver operating a system having adequate redundancy, rebreathers remain a great option for many divers.