I've been using GCD for a while now, but I was thinking about turning it off and just use the old vanilla level up system or at least another leveling system mod, since I heard GCD doesn't work well with hybrid classes.

Here's my experience of it -

I am playing a battlemage for a MQ playthrough and using GCD, and I absolutely love it for its magicka regeneration - other magicka regeneration mods seem too heavy handed, but GCD seems to have integrated it in a way that makes it seem really natural and fluid, and also makes building your regeneration rate up actually fun. I also really like the way everything is taken care of and behind the scenes, plus the attribute and skill level ups are way more satisfying that vanilla.

As for hybrids - it seems like if you spread your skills out more it just makes it slower to attain levels - which is not too bad a thing considering it gets quite easy at high levels imo. I do sometimes feel like I am being punished for not going full magic though, as my magic pool is not big enough to fight for long periods without resting/potions, which has led to me building up long blade too high, and use it too much, which I wouldn't have done had I had more magic.

I use http://planetelderscrolls.gamespy.com/View.php?view=Mods.Detail&id=7429. It gets rid of min/maxing and is compatible with just about every mod.

I've used GCD on at least half my characters since it came out but, as it happens, I just started a new character vanilla. It really isn't too different for a non-magic character (no regen for magicka) if you play normally. The traditional problem with vanilla is the temptation to powergame for max stats; at least for me, some people like that sort of thing. If you want to go vanilla, I recommend the mod SkilUpLedger to keep track of attributes.

I used GCD for a little awhile, but ultimately decided it just wasn't for me. I realized the only real problem I ever had with the vanilla leveling system was the lack of multiplier opportunities for Luck, which of course is easily remedied.

Nope. GCD isn't suited for me, as it change the way of levelling which i don't like. I just like the character development system of Morrowind as it is. You have the idea that you truly are developing your character step by step instead of being über at low levels like in Oblivion. I just like it when you are as slow as a turtle at level 1 and can defeat only barely a mudcrab or a rat and that you are totally owned in Addamasartus when entering it at level 1.

Speak for yourself getting pwned in that cave. I rip them a new one every time I start a new game.

But seriously, I know exactly what you mean. We've all been killed by a mudcrab a time or two, and I wouldn't have the start of the game be any other way. The only thing bothersome is when you essentially become a god past Level 40 or so, but mods can fix that.

I haven't difficulties too anymore in that cave, but i know that many characters from others have died there. Should one do the ironman way, then that cave would be a burial site for all the ironman chars.
And yep, in my first game i was killed by a slaughterfish, just in the water right after the lighthouse. I don't mind become a god or so at higher levels, because that's the purpose. Higher level means you become stronger.

If you use MCA it's very easy to die in addamasartus... in fact, unless you have some kind of uberpower mod, it's nearly impossible to do with a level one character. That's the thing about mods that make leveling and such more difficult. If you already use mods that place high powered foes, you are going to be constantly outclassed.