The only Khanid ship you'd ever seriously shield tank is the Curse, and that's because it's a EWAR ship and all EWAR ships have plenty of mids (the shield tanking slot in EVE).

I have been able to shield tank a few Amarr ships, like the Omen and the Arbitrator (again, EWAR), but no, they are not "one of true dual tankers in EVE." Sure, you can shoehorn any sort of tank onto any hull, but that doesn't mean it'll be effective or the best choice.

TL;DR : Khanid are Armor/Missile and the Amarr are overwhelmingly armor focused, save a couple of hulls. All of their tank bonuses are armor, be it damage resistance, armor rep amount, or buffer.

I understand from lore but its a nice buffer against grenade spammers and noob drivers

It is. I also felt it weird at first but the more I played the more it made sense. The Amarr assault suit is perfect as it is now. Amarr doctrine is about staying power, about presence and massive firepower, not about mobility or versatility. All this perfectly translate to the suit as it is now. No, having more armor than shields wont help you stay in the fight more because once your armor is damaged you are crippled. A balance between armor and shield, on the other hand, allows you to witstamd damage over time as well as provide buffer for critical situations. Those high slots are besy suited for damage mods, which our fittimgs stats allow, making for a deadly combatant. Add to it scramblers or LRs and thats what Amarr is about.

The gallenteans were always masters of the Armor, but we are masters of resilience and our suits withstand more punishment than theirs.

If you want more slots and the versatility it brings just switch races. If you want armor focused suits, the Gallente suits are there. Makimg the Amarr suits a copy of the Gallente ones is a bad move imo, I love them as they are, if you domt your desired option already exists. Go, and let the True Chosen be.

Oh, hi there Adamance. Switching isnt an option indeed, didnt notice that of all persons I was talking to you.

Yeah, it is weird, I know. I also learned to love armor tanking my ships in EVE, but in DUST dual tanking gives better results than pure armor from what I can tell so Im not complaining. It would also make us too similar to the gallente suits, I preffer the current model, but I know from where you are coming from.

Think this way: in the end the shield is just slightly better than normal, only worse than Caldari shields, while the armor is slightly worse than Gallenteans ones, which kind of makes sense lore wise. When fitted, if you use damage enhancers the natural complement is armor modules, which results in the Amarr ideal of lots of damage and armor. True there is more shield than normal, but it doesnt even compare in performance to that of a Caldari suit, plus it makes sense for our shields to be more sophisticated than that of the Minmatar for example. At least untill they fit dedicated shield modules, which they do, and make sense.

As for the slots... Its also pretty amarrish if you ask me. Tough, inflexible, in all ways, just like the Maller. Well, that is how I go about it at least. Think about it.

Omen is indeed a pretty decent cruiser, but I always liked the Arbitrator more. I mentioned the Maller because this discussion made me remind this, relevant quote below: