I did experience thermal runaway on a handful of small 5amp hour cells.
as for the idea that reverse charging can regain sulphate, i agree
the prior battery in my truck lasted a while, then decreased to uselessness, but it still had a 1.3 S.G.
I replaced it with a handful of used 5 amp hour agms.
I dumped the acid out of the truck battery, refilled it with water, and charged it with a 1 amp battery maintainer type charger for 3 months. Then left it disconnected for a month or two (because my brother needed the battery). The acid had increased to 1.2 as indicated by a cheap plastic electrolyte measuring device.
After the agms failed I put the truck battery back in my truck and.. i think got another year out of it, i can't recall.
anyhow, i do believe that permanent reverse charging is a significant permanent potential life saving treatment, because it stops the primary problem which is that the positive plate degrades to the point the plates break apart.