The first two are without flash. They are blurry, but the overall feel is a bit more real, like in place.
Now adding in-camera flash, things are not too bad, but getting flat...
In the following cases, the in-camera flash is really bad, as you can see the projected shadows behind the model, which just ruins everything.
@My Tip: If you plan to shoot more in future show events, spend some money and get an additional flash and soft cap/reflector, no matter how cheap they are. It's worth it.