I've been using a 430EX controlled wirelessly by my 60D pop-up flash (basically the same as 7D) since last October. I often hold the 60D in my right hand to shoot and hold the 430EX in my left hand above and partially to the side to get better off-camera lighting on the subject. Works perfectly every time. In fact, I'm so pleased with the 430EX that I just got a 430EX II so that I can do two-flash wireless set-ups using 60D wireless. I've done a couple hundred shots with these two flashes to explore A:B ratios, and they work excellently.
Incidentally, the line of sight requirement is not as big an issue as it might seem. Indoors in moderate size rooms you can often place your flash around the corner and still control it wirelessly due to reflections of the pop-up control flash. Outdoors, line of sight is important, but I've used it effectively even in sun on snow conditions at up to 25 feet. Worked perfectly every time.