Night elves have dodge, not miss chance.
A night elf rogue has openers that work for sub and assassination combat as well. It's most beneficial for subt. however.
I do notice that I can't just jam that button while running. I normally need to be planted for at least a moment before the meld/premed/cheap (or ambush, or garrote) works. You can also do sap like this.
I also recommend Dominoes or another button mod that will give you a stealth bar whilst melded, if you use the stealth bar.