I hope you get hit by a truck.
As for topic itself, while I personally adore the idea of a Shadowstep tier, I'd personally give Burst of Speed a sort of Vayne's passive. When you're 10 yards away from someone, it costs 20 energy. When you're 15 yards away, 30 energy; 20 yards, 60 energy; 30 yards, 80 energy; 40 yards, 100 energy.
It'd also be usable only while targetting someone who you've dealt damage to in past 20 seconds. As for crying about "how the fuck are we going to open then", use Sprint. I play a Rogue myself, I've completely removed Sprint from my bars, it'd give Sprint a reason to stay on your bars.