I haven't ridden the Slayblade, but have ridden the happy hour with flatline, and really wasn't a fan of flatline. To me, it felt slightly catchy, and had sort of a dead feel. My other problem with it, is that with all the rocker tech in boards now, not having it leaves something to be desired. Powder is always rider of board, but having a board that doesn't sink if you are being lazy is nice.
I agree with the above poster. Turbo Dream was a lot more fun for me.