Armor spells work well with the mage armour perks. Ebony flesh the expert level maxes out at an armor rating of 300 points with mage armor perk, and a duration 90 seconds with stability. The master spell only last 45 seconds with the stability perk, which kind of svcks but a solid 80% reduction is very useful.
I have never felt the need to use mage armor perks. Dragonhide doesnt care if you use armor or not, and a perked Ebonyflesh is only 300 armor, so eventually you just want armor anyway.
My mage used mage armor while leveling(so I didnt have to put perks in armor tree), but eventually I just leveled the armor skills.
I have to say that I always base my build around actual armour, then supplement it with mage armour. As many have said, mage armour never gets the armour cap, whereas real armour (plus smithing and enchanting) gets their easily. If destruction was a bit better then I might risk it, but almost all fights end up with an enemy in melee range, so you need proper protection.
Mage armor becomes obsolete quickly and doesn't get the hidden armor rating boost that wearing actual armor gives. It's terrible until dragonhide, but even dragonhide is a pain to cast all the time when you could effectively have it up 100% of the time with no downside if you just wore actual armor.
Real armor is better, mage armor doesn't even have any minor advantages to make it worth considering - even the lower weight of clothing doesn't make a difference when you can just wear elven and/or perk for 0 weight armor. It seems to be objectively inferior without much room for argument.
I've always considered mage armor a complete and utter waste of time, effort, and perks.
There is no difference between having Armor at the Armor Cap and walking around with Dragonhide cast. All of the Flesh spells including Ebonyflesh IMO are a way of covering Armor Rating lost to not equipping a Helm.
My Mages use Alteration to cover making mistakes, and because I enjoy walking up to almost defeated Mages with a Lightning Cloak Active and turning them into an Ashpile when they try to go melee, I have had a few characters take damage from higher tier Mages with Orcish/Elven Daggers. Paralysing an opponent is also a great benefit for a Skilled Alterationist.
This.
And this.
I think mage armour is useless. As hermit said there is no hidden bonus. So the cap is really 667. With all perks and lord stone you are looking at 350 armour. Some will say: Well that's over 50% reduction,but it does not work like that...it's still usless for the most part. It was better in morrowind and oblivion.
Dragonhide is fine accept the casting time,and being staggered ,but there are things to help this.Such as: Become etheral etc.
The game is catered to armour ,plain and simple. You can even make heavy armour lighter than clothes...and i do not agree with that at all.
Using dragonhide in combat is not practical at all due to cast time(its duration leaves a bit to be desired as well). I'd actually just as soon use a mage with 0 AC and try to avoid attacks(at least you save the magicka for damage)
Well that goes for most master spells, but I can stick it out with dragonhide because once you get it you get 80% damage reduction, very useful. Paralyze is also a great spell to use to set it up, 15 seconds of paralysis should buy you time. The problem with the spell is that it only last 45 seconds as opposed to 90 for all other armor spells, this is assuming you have the stability ability.
You're not even considering the huge amount of magicka required to even begin to think about casting the spell.....
Obviously you can enchant away some spell cost(not cast time though), but wouldn't you be better served enchanting armor with health or magicka or something else? Then you get the armor AND the stat bonus. There's really not much drawback to physical armor, but plenty of drawback to mage armor
Dual Casting requires a large Magicka Pool or Hefty Enchants, but a character ignores 80% of damage for 99 seconds with the Stability Perk.