I use them in battery back up systems on sump pumps, we install in the area of 200 batteries per year, some of these batteries are customer supplied some we buy, we have installed the full range of batteries, almost all but Penn. The battery is installed and we data base track them, we load test them at 4 years and suggest change out at 5 years. Why have a back up with a dead battery? We have a data base that covers roughly 500 batteries, Including marines, wet cells, Chinese AGMs, Optimas, the full range. The consensus is that on average, across the board that there has been a slightly higher failure rate among all AGM batteries, maybe 10%, wet cells are actually lasting a bit longer than the average, 6 years, most AGM's are reliable to about 5, then in a risk situation such as a basement flood they should be replaced. We NEVER open the batteries, we take them to a certified recycler, while GM has taken his batteries apart to discover what is wrong, I would advise against opening them up, honestly there is not much to see, it's not worth the danger of burning your self, trust his findings. They are correct and common to the failure of almost all AGMs. If you do open them they will not be covered by any warranty and the recycler charges you to take them. I suspect that across the board that there has been some type of a safety upgrade that is causing the terminal to erode under less stress. In my opinion it's a crap shoot as to what brand to buy, I suggest warranty be your guide, also try not to buy a huge cold cranking amp battery for a warm climate, high cca will just unduly stress your battery in a warm climate. If all else fails, the wet cells are performing well by my data base.