I have never had a leak of my BCD, but I had a Mares jacket and lost a weight pocket three times, the first time was during a training dive and I could hold on to a wreck (I was just observing). After I replaced it, the next dive, it fell out as I entered the water. Then it was fixed by Mares, but a year later I lost it again (always the same pocket). I think I used the Mares BCD on approximately 500 dives. As this really annoyed me I replaced it after this last incident. Sold it to a dive shop btw.
I had an unstoppable free flow twice with the same Mares Proton regulator. It was serviced. The shop told me I should ditch it as fixing it would not solve the problem in the long run. Something with coating that had come off. I bought it at the same time as the jacket so it died too after approx. 500 dives as it was around the same time as the BCD failure.
My wife had an inflator replaced some years ago. It wouldn't inflate during a dive, so she used her drysuit for buoyancy. so This was once in 1500 dives. It was her first BCD and she had used it for 12 years. As the part were no longer available it was replaced because of this (it was worn too)
She also had to replace her neoprene dry suit after 14 years as it was leaking so badly she came out wet on every dive. At a test they inflated it, and this was filmed, we saw that most of the seams were leaking.
So all in all we had very few failures.