The difference isn't that big. Consider the elven and dwarven armors, both found from lvl 12:
A full set of elven armor gives 58 base armor + the 100 hidden = 18,96% reduction
A full dwarven set gives 78 base, +100 = 21,36% reduction.

Thank you! this response is immensely helpful.

I'm planning on creating a Bard class, based on Oblivion's model, using illusion primarily to cause chaos, calm, or turn invisible, and then taking out the sword and shield in light armor for effective one-on-one melee encounters. That's what i'm after... i already have illusion and blade sneak attacks, but both of those are already highly effective in all encounters that are already easy enough - they just won't work well at all on dragons. Sword and shield it is!

interesting. where did you find this information about the "100 hidden" armor rating? is that based on perks or skill level, or how many pieces of a type of armor are being worn? i.e., will you get the 100 hidden rating if you wear all elven except the helmet, or maybe some pieces of elven and some of glass?

You get 25 extra armor per armor pieces worn (some sources say 40 for chest and 20 for helm/boots/gloves).
Your actual damage reduction is your displayed armor rating (open your apparel tab to see this) + hidden armor rating * 0,12.

Lots of additional info http://www.uesp.net/wiki/Skyrim:Armor.

Light armor redguard warrior here. I have no problems fighting Dragons either. Of course i use a bow to wear them down then rush in with twohander or sword and shield. I love my Dragon fights. Just killed one in a town which was sweet. Everyone was running away but me.

no the best defense is good offense..if you got a strong sword arm, doubling up with the dual weild power attack will chop all down before they can do any real damage. I usually wait for a dragon to land then hit him in the side/wing with power attacks that stagger him..he usually never leaves the ground once he lands.

IMO a shield is only useful when fighting a shielded opponent or if your health is running low

I guess I should add I'm playing on Master, changes the rules a bit. I feel much safer with a shield.

Using a Dual Wield + light armor guy with no sneak skill...

Dragons have *never* posed a significant challenge after the 1st one.

my next build will be a light armor mage/1handed swords man. No shield. No Dual Wielding. It should provide more challange. haha

Me again, just had to report back in about the effectiveness of the build, on expert difficulty.

conclusion: lightly armored characters are basically forced to use ranged weapons, OR specialize exclusively into pure combat skills, thus eliminating the possibility of hybrid style play.

i'm not sure what game you all are playing, but at level 18 i am getting ANNIHILATED by frost dragons, mages, etc. it is so broken that it isn't even funny, and the difference between this character, and my previous conjuration/archery character is just ridiculous. i have had to resort to self-enchanted, stamina absorbing swords to fuel continual shield bashing, and even then, dragons (instant kill bite animation) and some spell casters (ice storm) will one-shot me, in elven armor. my only guess is that my health is much too low for my level, as i have been doing 3/1/1 every five levels, for about 150 health after enchantments. the ridiculous thing is, if the dragon instant-kill is based on total health, then they are forcing melee characters to pump health (and stamina) in order to be viable - this means no hybrid builds such as the one i am trying to make. i couldn't even imagine trying to do this with dual-wielding, which must be essentially impossible.

recommendations: light armor is for ranged. if you want to do melee, or make a melee fighter hybrid, use heavy armor or alteration spells.

this is just so disappointing. Bethesda should have playtested their game before releasing it.

Edit: sadly, i've almost had enough with this game. the bugged quests, crappy watered-down magic system, and total lack of balancing (certain skills naturally become overpowered, some encounters are cakewalks, some are impossible with certain builds, no flexibility) are highly, highly disappointing, and i've tried very hard to extract enjoyment out of this.

the bottom line is, i'm not able to play as i wanted. i've restarted many, many times trying to find builds that don't automatically become god-mode overpowered, or incapable of defeating essential encounters. there is no in-between, it's one or the other.

Rock, paper, scissors. Certain builds are always going to be overpowered against certain enemies, and gimped against others. As to the effectiveness of dual-wielding, my dual wielding thief was having survivability issues around level 23 or so, and I had to start investing in smithing. Unfortunately, I had to cheese my smithing level up to 50 or so by making lots of gauntlets. But now my thief doesn't go down in 2 or 3 hits and I didn't have to dial down the difficulty, so it was worth it.