In reading all of this, people are really caught up in a debate that has already been settled. SSDs are here and they are safe for enterprise storage needs. That point I don't think can be debated. The reason I say this is because they are used by nearly every storage manufacturer for almost any application.
The question brought up is around how they fail and what risk might be introduced by their failure scenarios. In a general sense that was all the issue that came from the transition from Enterprise SCSI and FC drives to IDE/SATA technology. SATA drives in general fail less predictably than an EFC (enterprise Fibre Channel drive). I don't have any test data to support this, but I've talked to very seasoned storage and disk engineers and they have all confirmed this. The issue is that with larger drives and longer rebuild times, you might have more potential for double disk failure because drives wouldn't have been prefailed out early like they are with EFC drives. To help shore up this discontinuity they introduced the RAID 6 or added parity RAID schemes that could withstand 2 simultaneous failures.
In the world of SSD drives you have much smaller data sets, so much less data needs to be rebuild, in addition to that, the drives are much faster, so rebuild times are really short. That means that you have a smaller window of time for that second drive to fail in and thus a lower probability that you will have 2 drives fail in that exact window. I can't do all of the math, but the probability drops off pretty fast as the rebuild times go up.
The point of an earlier post was...I think...that SSD only live for 100,000 write ops or whatever and if you put two of them in at the same time, they would hit 100,000 ops at about the same time. But this misses two points. 1) Drives aren't necessarily doing the same exact amount of iops and 2) that 100,000 number isn't an exact number...it's an expected number. Some might get 150,000 some might get 90,000, it depends on the drive. That said, the likelihood is remote and no larger than other storage types that you would have a DD failure cause data loss with SSDs over other storage types.
Lastly, with enterprise solutions, you are covered by the mfg warranty, so when or if a disk fails in say 1.4 years, it will be replaced with a new one and off you go. That's why you buy integrated systems from good vendors. They will build reliable systems for you and support them for their useful life.