Took the word out of my mouth, I was thinking the same thing:
Musaaaaaaa Moo Hyuuuuuuul!!!

I don't know if it really will be a dark drama. The writer some weeks ago said it will be leighthearted. But as it is obviously influenced by the recent political events in Korea it will definitely be a more serious drama than the ones you mentioned. By the way, I dropped the same dramas. :) - Except Moon Lovers which I couldn't drop because I didn't even start it. ;)

I liked the changes they made to the classical Hong Gil-dong novel. Making Hong Gil-dong's dad a lowborn too, does take away the focus of the story from the halfborn noblemen's sons and their struggles. In accordance it was good to leave out the "Book of Changes" and just give Hong Gil-dong some extraordinairy strength he was born with. You can still use it to tell a tale about what to do with power and incorperate the elements of the story in which Hong Gil-dong's special powers were important.
As they wanted to tell a story about leadership, it was also good that they changed the time. The classical story takes place during the reign of King Sejong (it was written a little bit later though - there are different theories when and by whom it was written), who wouldn't have been a good example for a leader who is NOT a good leader of the people. King Yeonsan definitely isn't seen as a good leader and he still has a connection to Hong Gil-dong as he is the King during whos reign the historical robber Hong Gil-dong was active.

I've been looking forward to seeing Kim Ji-suk in another sageuk since his turn as the randy but goodhearted ladies' man Wang-Son in CHUNO. After his hilarious romantic misadventures in OH HAE-YOUNG AGAIN, seeing him morph into Yeonsangun will be a treat. He looks great in kingly raiment.

Still have yet to watch SIX FLYING DRAGONS, but got a kick out of Yoon Kyun-sang in THREE MEALS A DAY.

Aside from the righteous thieves in the two ILJIMAEs, and HYANGDAN, I haven't actually seen Hong Gil-dong portrayed yet, either. Might have time to sneak it in before REBEL premieres. The DB rating for the 2008 version makes me think I should give it a go. ;-)

They seem to keep making this mistake, I've seen it pointed out in other posts before.

My country's too new to have a very interesting history, and somehow paranoid kings, scheming queens, sassy princesses and handsome princes scoop my interest a lot more than a few hundred years of bureaucrats and prime ministers. I like deep histories and all the strange social systems they had in some of these countries. I know a lot about Korean history now, and I'm expanding that interest into China now. Places I had little interest in learning about before I started watching kdramas!

No need to feel guilty. It actually gives you a broader perspective to then consider your own country's history. In fact, global history is one of the most exciting new developments (for me) in universities. I used to be interested in only European and American history, thinking that Asia was just too complex for me. Thanks to kdrama I've slowly started to learn about Korean and Chinese characters and dynasties. Actually, I'm going to a lecture on Ming pottery next week so in a way kdrama has broadened my academic horizons (I've just justified my drama procrastination syndrome too, yay!).

I love it when two dramas help me piece together bits of history. For example, I happened to watch Empress Ki and Faith one after the other. Neither were actually very 'historical', I realised after doing some research, but they made me look into China and the Korean peninsula more closely towards the end of the Yuan dynasty, 14th century.

And when my historical worlds collide, it's just amazing. I still remember a scene in Queen Seon Deok where merchants from Rome (would have been the Byzantine Empire by then, 7th century) were speaking in Latin with their Asian counterparts in the middle of the desert. I was dumstruck. We forget that there were global connections before the Internet. :D