The problem is I dont think many have been using AGMs for that long, so the jury may still be out. I can tell you that I now have 4 years out of mine and they are still going strong. For me its worth the extra expense if I dont have to keep an eye on the water levels, assuming that I also get decent service life out of them. In my previous MH I was always messing with those (4) 6 volts which were all wet cells. I even installed one of those automatic refill kits to make life easier but it was still a pain.