What about dendrite reversal, better or worse?

Dendrite formation happens through lack of use. The dendrites form and bridge a path through the matting from one plate to the other... and create a short. So really the AGM material versus the "standard" separator material wouldn't really make a difference. They are BOTH porous. The only way to eliminate dendrite bridging would be to have an impervious membrane between the plates (ie in place of the glass mat), but you need the porosity for the electrons to flow. Without electron flow you have nothing.

As far as the GEL's effect on dendrite, I'm not sure... we were just getting into that line of battery when I lost my employment there. I had been involved with implementing the line, and we only produced a couple thousand batteries before then. I'm sure that the line prolonged my employment with the company, because once it was up and running, they cut the entire engineering department.

In all, the best way to eliminate dendrite formation is to just give your batteries a workout... don't let them sit. As far as reversal, a shot of high current charging is supposed to "reverse" dendrite formation, but often it just blasts them loose to suspend in the electrolyte, where they can hang up in the matting and bridge right back again. Think of it like a fuse. If you give it a high enough voltage/amperage you can incinerate the whole filament. But mostly you just fry a little gap in it.

So I guess to sum it up, I'm sorry but I just don't have enough input on the battery type's impact on dendrite susceptibility to help you out, but that's about what I know.

My two thoughts, were the mat would act as either a bridge to aid in them or as a barrier preventing them. I always see batteries in reversal that won't take a charge, but of the 5 or 6 agm's I have had this never happened. That's why I asked, just idle curiosity.

Well, you are correct... the mat's original job is to separate the plates, so they don't move and/or contact each other, and short. (On the assembly line it was called separator material.) It additionally helps in that it also packs everything nice and tight inside the case to reduce the possibility that vibrations/jolts would break the active material off the lead grids, or even break the grids themselves. And then lastly, being absorptive helps keep the plates wet (like a sponge), keeping the performance up and battery life long.