I wouldn't think 50mm at 30m is sufficient.
Oh, a point that I missed out. Each method has its own shortcomings.
1. Larger apertures will lead to shallower depth of field. This may be desirable in some cases, but terrible in others.
2. Higher ISO leads to more noise. Enough said.
3. 1 flash unit, no matter how big it is, is probably not able to light up the entire scene. It is here that your control of flash lighting becomes crucial. Unfortunately, there doesn't seem to be anywhere else to pick up the skill but at the event itself. In addition, certain events forbid the use of flash.
4. Shutter speeds have to be kept fast enough to avoid motion blur, a problem that the Super Steady Shot cannot save.
If it's any help, here's what I do for concerts:
1. My Lenses:
- Tamron SP AF 17-50mm F/2.8 XR Di II LD Aspherical [IF]
- Nikon AF-S DX VR Zoom-Nikkor 55-200mm f/4-5.6G IF-ED
- Nikon SB-600 Speedlight
As you can see, mostly "cheapo" gear. I'd prefer a 70-200mm f/2.8 VR, but, alas, cannot afford that. In your case, I recommended the Sony equivalent in my earlier post.
2. My Preferred Setting:
Aperture: Largest Possible
Shutter Speed: > 1/20s
ISO: < 800
3. Flash
Direct, most of the time.
I do change my settings and gear to fit the situation, but I suppose this is a fair general guide.