Does the armor rating from the helmet and body stack, or is there a cap for each kind of defense? For example, would wielding a Divine Veil and a Skolver coat make you the "jack of all trades, master of none" in terms of defense (compared to wielding the divine set or the skolver set and forgoing the other two types of defense).
And if it does, which is better?
Thanks.
The jack-of-all-trades setup is viable but not optimal. When entering a strata, it is likely that you'll mostly encounter only two kinds of damage... in a beast strata that would be Normal/Piercing, in a Fiend strata that would be Normal/Shadow, etc
There are a lot of important exceptions to what you wrote. For example, today I did a poison stratum, where I ran into wolvers, lumbers, devilites, retrodes and greavers. Yeah, most of them could do poison, but that's about all they have in common. Even a stratum like beasts, you can easily get elemental damage along with your normal/piercing.
In this game, you can't be a brick wall. You can, however, be killed in just a few blows. Something that can keep you from dying so that you can get to the next heart can be much more useful than something that usually lets you leave hearts on the ground but you die if you make a mistake around the wrong monster.
I think what people think is "best" is often just what they are used to. If you wander around without, say, shadow defense, you just get really careful about not getting hit by stuff that does shadow damage, at which point, you can publicly dismiss the need for armor that has shadow defense because it is "easy to avoid". (Replace shadow with piercing, or freeze resistance, or whatever.)
What did you end up wearing into that Poison strata since it does so many different types of damage?
When I see a strata that has a heavy mix I just put on some Normal/Elemental and hop in. I know everything else is easy to avoid ;) If it is a Fire or Shock Strata then I might choose something that resists those statuses. With the recent shock nerf, even that isn't necessary though.
Defenses from the helm and armor do stack. There does not appear to be a maximum cap, your defenses can even extend beyond the end of the visible bar and still take effect.
The jack-of-all-trades setup is viable but not optimal. When entering a strata, it is likely that you'll mostly encounter only two kinds of damage... in a beast strata that would be Normal/Piercing, in a Fiend strata that would be Normal/Shadow, etc. Typically you'll want to dress for the damage you'll be facing.
That said, if I had to choose just two damage types to defend against it would be Normal and Elemental. Normal is everywhere. Elemental comes up a lot due to the always-lucrative Arenas being full of bots and gun puppies. It isn't absolutely necessary to go only Normal/Elemental though, especially if the alternative armors provide some bonuses that could outweigh defense provided.