Almost got to stage 6 on my first attempt at 1 CC on Hard Mode with life bars and perks. Just completed the Hard, 1 hit kill mode and posted up a tutorial. This game is addictive. I think I will wait until I complete this 1 CC run on Hard, and then I will make another tutorial for that. It would be redundant to add commentary over my quicker run through Hard, 1 hit death mode with Browny.
Main barrier for me is going to be getting the wrong weapon pick ups on the 5th stage, I think. Its tough not to get a bad loadout since the weapon capsules are frequently floating in your path, and you cant take the time to avoid them mid air, or set up your loadout properly.