yeah I've got it now... I've even manged to score a 570K surprise... Challenge 20 on Level 1...
500 for hiding
x5 hunger
x4 flourish
x3 Range
x19 combo

I had to stop playing it though, I love the game but the inability to change the inversion of the X and Y axis REALLY screws me up.
I had trouble controlling it for a while, by the time I re-trained myself to work the way the game was programed my buddy came over to play some Gears of War to work on playing through on Insane.... yeah that didn't go over too hot.
I'm in GOW mode right now, so I don't think I'll return to sneak king until I'm done with GOW.