I'm trying to figure out something for a project that's upcoming. I'd like two flashes on stage (maybe three) triggered by an ST-E2 on-camera from the back of the room and various places in-between. Will they work in this situation to meter the flash output? If not are there any alternative flashes in that price range ($150 each) that would work. Or if anyone has a better idea I'm quite open to listening and learning. I'm new to this.
Yongnuo claims that it will; whether or not it will work reliably in your situation will be a matter of experimentation. Off-brand is off-brand, and compatibility/reliability are always a little bit hit-and-miss. When it hits, you're golden, but there's always a question of forward-compatibility, so what works wonderfully today may not work tomorrow. Still, if you can save something on the order of $500/unit, expediency today may make a lot more sense than 100% compatibility with your next camera.