First: Normal, around 6 hours, 64% items ----> this file went on to be my 100%
Second: Insane, around 4 hour, 67% items ----> level up run
Third: Insane, around 4 hour, 72% items ----> level up run 
Fourth: Normal, 1:52, 10% items -----> minimalist run
Fifth: incomplete ----> gained last two level need to 50
 
I was surprised how fast my minimal run went but it basically dashed my hopes of going for the master Challenges except for "Status Update: Single."

First: Normal, around 7 hours, 87% of items
Second: Normal, 4:30, 100% of items (I just finished this)
 
I'm probably going to do my minimalist/single run next. Does playing on insane give more EXP?

First: Normal, around 6 hours, 52% items -> got to 99% and realized that I missed the Inertial Element/Shotgun.
Now I'm debating whether to do just a minimalist run or go all over 100% again.
 
@Hannibal: Yes, Insane gives more EXP.

I'm about half way through my first run on Hardcore. I have about half the items collected too. I'm also already in the low 20s in terms of my level so I guess it starts to get super hard to level later.

Wow. 5 playthroughs. 
 
Doesn't compare to me playing MGS4 like 11 times though.

#1... 15 hours, ... but really probably about 8-9 with completionist.  I've got a bad habit of leaving games on all day while i'm browsing the web or if I leave the house for a few hours. 
#2...  3:39:01 | 3,285,409 pts | 12%

so far i've beaten it once on normal with 75% of items. It took about 6 hours

My first on normal, 4:47, collected only 41%
Second on Hardened, 4:30, collected 61%

First: Normal - 12 hours - 99% (Damn missable gun) 
Second: Hardcore - 5 hours - 100% 
Third: Normal - 3 hours - 13% 
Fourth: Insane - In progress. 
I'm at Level 40 right now. 

First: Hardcore - around 8 hours, 100%
Second: Normal, minimalist run,  around 1 hour 30 minutes, 12%

First: Insane, little over 12 hours, 100%
Second: Casual, 1:35, 11%
 
I'll probably do one more run on Insane to get my last 8 levels, but I think after that I'll be done with Shadow Complex for a while.

First: Hardcore - ~7 hours - ~70%
Second: Hardcore - ~6 hours - 99% (missed the damn Inertial Element)
Third: Hardcore - ~15 mins - Got the joke ending
Fourth: Casual - ~1 hour - 3% 
 
Now all I need to do is a 100% run through and get about 5 more levels to get to 50.

I stupidly started a new game after collecting only around 70% of items, oblivious to the fact that I could have gone back to get the rest of the missing items easily. Now I have to find those 70% all over again. Sigh. At least I'll know where everything is for the most part.

First: Hardcore, 11 hours 40 minutes, 100% items
 
I'm gonna start a second playthrough and go for less than 13% items on Hardcore

First: Played on Insane, was going to go for 100%, but missed the Inertial Element; ended around level 32.
Second: Playing through on Insane (dumping down to normal in parts to save time), almost at 100%; at level 43 right now.
Third: Planning on getting Minimalist (probably will try at 4%)

 
First: Normal, 100% About 7 hours.
Second: Casual 13% Just over an hour.
Third: Casual 12% 54:14
Fourth: Casual 4% 38:22
Fifth: Casual 5% 33:07
Sixth: Casual 5% 27:00
 
Pretty much just seeing how fast I can plow through the game. Was 2nd place behind Hilary before the sequence break was found out.

Just did my second run.  My goal was to finish the game under two and a half hours and I ended up beating it in two hours and twenty nine minutes